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FAILED: patch "[PATCH] KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 7d0cce6cbe71af6e9c1831bff101a2b9c249c4a2 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081216-ointment-common-3721@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 7d0cce6cbe71af6e9c1831bff101a2b9c249c4a2 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky <mlevitsk(a)redhat.com> Date: Tue, 10 Jun 2025 16:20:09 -0700 Subject: [PATCH] KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with getter/setter APIs Introduce vmx_guest_debugctl_{read,write}() to handle all accesses to vmcs.GUEST_IA32_DEBUGCTL. This will allow stuffing FREEZE_IN_SMM into GUEST_IA32_DEBUGCTL based on the host setting without bleeding the state into the guest, and without needing to copy+paste the FREEZE_IN_SMM logic into every patch that accesses GUEST_IA32_DEBUGCTL. No functional change intended. Cc: stable(a)vger.kernel.org Signed-off-by: Maxim Levitsky <mlevitsk(a)redhat.com> [sean: massage changelog, make inline, use in all prepare_vmcs02() cases] Reviewed-by: Dapeng Mi <dapeng1.mi(a)linux.intel.com> Link: https://lore.kernel.org/r/20250610232010.162191-8-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 1b8b0642fc2d..ef20184b8b11 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2663,11 +2663,11 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, if (vmx->nested.nested_run_pending && (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) { kvm_set_dr(vcpu, 7, vmcs12->guest_dr7); - vmcs_write64(GUEST_IA32_DEBUGCTL, vmcs12->guest_ia32_debugctl & - vmx_get_supported_debugctl(vcpu, false)); + vmx_guest_debugctl_write(vcpu, vmcs12->guest_ia32_debugctl & + vmx_get_supported_debugctl(vcpu, false)); } else { kvm_set_dr(vcpu, 7, vcpu->arch.dr7); - vmcs_write64(GUEST_IA32_DEBUGCTL, vmx->nested.pre_vmenter_debugctl); + vmx_guest_debugctl_write(vcpu, vmx->nested.pre_vmenter_debugctl); } if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending || !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))) @@ -3532,7 +3532,7 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, if (!vmx->nested.nested_run_pending || !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) - vmx->nested.pre_vmenter_debugctl = vmcs_read64(GUEST_IA32_DEBUGCTL); + vmx->nested.pre_vmenter_debugctl = vmx_guest_debugctl_read(); if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending || !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))) @@ -4806,7 +4806,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, __vmx_set_segment(vcpu, &seg, VCPU_SREG_LDTR); kvm_set_dr(vcpu, 7, 0x400); - vmcs_write64(GUEST_IA32_DEBUGCTL, 0); + vmx_guest_debugctl_write(vcpu, 0); if (nested_vmx_load_msr(vcpu, vmcs12->vm_exit_msr_load_addr, vmcs12->vm_exit_msr_load_count)) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index bbf4509f32d0..0b173602821b 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -653,11 +653,11 @@ static void intel_pmu_reset(struct kvm_vcpu *vcpu) */ static void intel_pmu_legacy_freezing_lbrs_on_pmi(struct kvm_vcpu *vcpu) { - u64 data = vmcs_read64(GUEST_IA32_DEBUGCTL); + u64 data = vmx_guest_debugctl_read(); if (data & DEBUGCTLMSR_FREEZE_LBRS_ON_PMI) { data &= ~DEBUGCTLMSR_LBR; - vmcs_write64(GUEST_IA32_DEBUGCTL, data); + vmx_guest_debugctl_write(vcpu, data); } } @@ -730,7 +730,7 @@ void vmx_passthrough_lbr_msrs(struct kvm_vcpu *vcpu) if (!lbr_desc->event) { vmx_disable_lbr_msrs_passthrough(vcpu); - if (vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR) + if (vmx_guest_debugctl_read() & DEBUGCTLMSR_LBR) goto warn; if (test_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use)) goto warn; @@ -752,7 +752,7 @@ void vmx_passthrough_lbr_msrs(struct kvm_vcpu *vcpu) static void intel_pmu_cleanup(struct kvm_vcpu *vcpu) { - if (!(vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR)) + if (!(vmx_guest_debugctl_read() & DEBUGCTLMSR_LBR)) intel_pmu_release_guest_lbr_event(vcpu); } diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 6a8b78e954cd..a77d325fe78b 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2149,7 +2149,7 @@ int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) msr_info->data = vmx->pt_desc.guest.addr_a[index / 2]; break; case MSR_IA32_DEBUGCTLMSR: - msr_info->data = vmcs_read64(GUEST_IA32_DEBUGCTL); + msr_info->data = vmx_guest_debugctl_read(); break; default: find_uret_msr: @@ -2283,7 +2283,8 @@ int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) VM_EXIT_SAVE_DEBUG_CONTROLS) get_vmcs12(vcpu)->guest_ia32_debugctl = data; - vmcs_write64(GUEST_IA32_DEBUGCTL, data); + vmx_guest_debugctl_write(vcpu, data); + if (intel_pmu_lbr_is_enabled(vcpu) && !to_vmx(vcpu)->lbr_desc.event && (data & DEBUGCTLMSR_LBR)) intel_pmu_create_guest_lbr_event(vcpu); @@ -4798,7 +4799,8 @@ static void init_vmcs(struct vcpu_vmx *vmx) vmcs_write32(GUEST_SYSENTER_CS, 0); vmcs_writel(GUEST_SYSENTER_ESP, 0); vmcs_writel(GUEST_SYSENTER_EIP, 0); - vmcs_write64(GUEST_IA32_DEBUGCTL, 0); + + vmx_guest_debugctl_write(&vmx->vcpu, 0); if (cpu_has_vmx_tpr_shadow()) { vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, 0); diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 392e66c7e5fe..c20a4185d10a 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -417,6 +417,16 @@ void vmx_update_cpu_dirty_logging(struct kvm_vcpu *vcpu); u64 vmx_get_supported_debugctl(struct kvm_vcpu *vcpu, bool host_initiated); bool vmx_is_valid_debugctl(struct kvm_vcpu *vcpu, u64 data, bool host_initiated); +static inline void vmx_guest_debugctl_write(struct kvm_vcpu *vcpu, u64 val) +{ + vmcs_write64(GUEST_IA32_DEBUGCTL, val); +} + +static inline u64 vmx_guest_debugctl_read(void) +{ + return vmcs_read64(GUEST_IA32_DEBUGCTL); +} + /* * Note, early Intel manuals have the write-low and read-high bitmap offsets * the wrong way round. The bitmaps control MSRs 0x00000000-0x00001fff and

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FAILED: patch "[PATCH] KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 7d0cce6cbe71af6e9c1831bff101a2b9c249c4a2 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081215-prance-palatable-01ab@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 7d0cce6cbe71af6e9c1831bff101a2b9c249c4a2 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky <mlevitsk(a)redhat.com> Date: Tue, 10 Jun 2025 16:20:09 -0700 Subject: [PATCH] KVM: VMX: Wrap all accesses to IA32_DEBUGCTL with getter/setter APIs Introduce vmx_guest_debugctl_{read,write}() to handle all accesses to vmcs.GUEST_IA32_DEBUGCTL. This will allow stuffing FREEZE_IN_SMM into GUEST_IA32_DEBUGCTL based on the host setting without bleeding the state into the guest, and without needing to copy+paste the FREEZE_IN_SMM logic into every patch that accesses GUEST_IA32_DEBUGCTL. No functional change intended. Cc: stable(a)vger.kernel.org Signed-off-by: Maxim Levitsky <mlevitsk(a)redhat.com> [sean: massage changelog, make inline, use in all prepare_vmcs02() cases] Reviewed-by: Dapeng Mi <dapeng1.mi(a)linux.intel.com> Link: https://lore.kernel.org/r/20250610232010.162191-8-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index 1b8b0642fc2d..ef20184b8b11 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -2663,11 +2663,11 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, if (vmx->nested.nested_run_pending && (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) { kvm_set_dr(vcpu, 7, vmcs12->guest_dr7); - vmcs_write64(GUEST_IA32_DEBUGCTL, vmcs12->guest_ia32_debugctl & - vmx_get_supported_debugctl(vcpu, false)); + vmx_guest_debugctl_write(vcpu, vmcs12->guest_ia32_debugctl & + vmx_get_supported_debugctl(vcpu, false)); } else { kvm_set_dr(vcpu, 7, vcpu->arch.dr7); - vmcs_write64(GUEST_IA32_DEBUGCTL, vmx->nested.pre_vmenter_debugctl); + vmx_guest_debugctl_write(vcpu, vmx->nested.pre_vmenter_debugctl); } if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending || !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))) @@ -3532,7 +3532,7 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu, if (!vmx->nested.nested_run_pending || !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_DEBUG_CONTROLS)) - vmx->nested.pre_vmenter_debugctl = vmcs_read64(GUEST_IA32_DEBUGCTL); + vmx->nested.pre_vmenter_debugctl = vmx_guest_debugctl_read(); if (kvm_mpx_supported() && (!vmx->nested.nested_run_pending || !(vmcs12->vm_entry_controls & VM_ENTRY_LOAD_BNDCFGS))) @@ -4806,7 +4806,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu, __vmx_set_segment(vcpu, &seg, VCPU_SREG_LDTR); kvm_set_dr(vcpu, 7, 0x400); - vmcs_write64(GUEST_IA32_DEBUGCTL, 0); + vmx_guest_debugctl_write(vcpu, 0); if (nested_vmx_load_msr(vcpu, vmcs12->vm_exit_msr_load_addr, vmcs12->vm_exit_msr_load_count)) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index bbf4509f32d0..0b173602821b 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -653,11 +653,11 @@ static void intel_pmu_reset(struct kvm_vcpu *vcpu) */ static void intel_pmu_legacy_freezing_lbrs_on_pmi(struct kvm_vcpu *vcpu) { - u64 data = vmcs_read64(GUEST_IA32_DEBUGCTL); + u64 data = vmx_guest_debugctl_read(); if (data & DEBUGCTLMSR_FREEZE_LBRS_ON_PMI) { data &= ~DEBUGCTLMSR_LBR; - vmcs_write64(GUEST_IA32_DEBUGCTL, data); + vmx_guest_debugctl_write(vcpu, data); } } @@ -730,7 +730,7 @@ void vmx_passthrough_lbr_msrs(struct kvm_vcpu *vcpu) if (!lbr_desc->event) { vmx_disable_lbr_msrs_passthrough(vcpu); - if (vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR) + if (vmx_guest_debugctl_read() & DEBUGCTLMSR_LBR) goto warn; if (test_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use)) goto warn; @@ -752,7 +752,7 @@ void vmx_passthrough_lbr_msrs(struct kvm_vcpu *vcpu) static void intel_pmu_cleanup(struct kvm_vcpu *vcpu) { - if (!(vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR)) + if (!(vmx_guest_debugctl_read() & DEBUGCTLMSR_LBR)) intel_pmu_release_guest_lbr_event(vcpu); } diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 6a8b78e954cd..a77d325fe78b 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2149,7 +2149,7 @@ int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) msr_info->data = vmx->pt_desc.guest.addr_a[index / 2]; break; case MSR_IA32_DEBUGCTLMSR: - msr_info->data = vmcs_read64(GUEST_IA32_DEBUGCTL); + msr_info->data = vmx_guest_debugctl_read(); break; default: find_uret_msr: @@ -2283,7 +2283,8 @@ int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) VM_EXIT_SAVE_DEBUG_CONTROLS) get_vmcs12(vcpu)->guest_ia32_debugctl = data; - vmcs_write64(GUEST_IA32_DEBUGCTL, data); + vmx_guest_debugctl_write(vcpu, data); + if (intel_pmu_lbr_is_enabled(vcpu) && !to_vmx(vcpu)->lbr_desc.event && (data & DEBUGCTLMSR_LBR)) intel_pmu_create_guest_lbr_event(vcpu); @@ -4798,7 +4799,8 @@ static void init_vmcs(struct vcpu_vmx *vmx) vmcs_write32(GUEST_SYSENTER_CS, 0); vmcs_writel(GUEST_SYSENTER_ESP, 0); vmcs_writel(GUEST_SYSENTER_EIP, 0); - vmcs_write64(GUEST_IA32_DEBUGCTL, 0); + + vmx_guest_debugctl_write(&vmx->vcpu, 0); if (cpu_has_vmx_tpr_shadow()) { vmcs_write64(VIRTUAL_APIC_PAGE_ADDR, 0); diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h index 392e66c7e5fe..c20a4185d10a 100644 --- a/arch/x86/kvm/vmx/vmx.h +++ b/arch/x86/kvm/vmx/vmx.h @@ -417,6 +417,16 @@ void vmx_update_cpu_dirty_logging(struct kvm_vcpu *vcpu); u64 vmx_get_supported_debugctl(struct kvm_vcpu *vcpu, bool host_initiated); bool vmx_is_valid_debugctl(struct kvm_vcpu *vcpu, u64 data, bool host_initiated); +static inline void vmx_guest_debugctl_write(struct kvm_vcpu *vcpu, u64 val) +{ + vmcs_write64(GUEST_IA32_DEBUGCTL, val); +} + +static inline u64 vmx_guest_debugctl_read(void) +{ + return vmcs_read64(GUEST_IA32_DEBUGCTL); +} + /* * Note, early Intel manuals have the write-low and read-high bitmap offsets * the wrong way round. The bitmaps control MSRs 0x00000000-0x00001fff and

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FAILED: patch "[PATCH] KVM: arm64: Filter out HCR_EL2 bits when running in" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x 303084ad12767db64c84ba8fcd0450aec38c8534 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081259-clutter-elusive-1a09@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 303084ad12767db64c84ba8fcd0450aec38c8534 Mon Sep 17 00:00:00 2001 From: Marc Zyngier <maz(a)kernel.org> Date: Mon, 21 Jul 2025 11:19:50 +0100 Subject: [PATCH] KVM: arm64: Filter out HCR_EL2 bits when running in hypervisor context Most HCR_EL2 bits are not supposed to affect EL2 at all, but only the guest. However, we gladly merge these bits with the host's HCR_EL2 configuration, irrespective of entering L1 or L2. This leads to some funky behaviour, such as L1 trying to inject a virtual SError for L2, and getting a taste of its own medecine. Not quite what the architecture anticipated. In the end, the only bits that matter are those we have defined as invariants, either because we've made them RESx (E2H, HCD...), or that we actively refuse to merge because the mess with KVM's own logic. Use the sanitisation infrastructure to get the RES1 bits, and let things rip in a safer way. Fixes: 04ab519bb86df ("KVM: arm64: nv: Configure HCR_EL2 for FEAT_NV2") Signed-off-by: Marc Zyngier <maz(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20250721101955.535159-3-maz@kernel.org Signed-off-by: Oliver Upton <oliver.upton(a)linux.dev> diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index 477f1580ffea..e482181c6632 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -48,8 +48,7 @@ DEFINE_PER_CPU(unsigned long, kvm_hyp_vector); static u64 __compute_hcr(struct kvm_vcpu *vcpu) { - u64 guest_hcr = __vcpu_sys_reg(vcpu, HCR_EL2); - u64 hcr = vcpu->arch.hcr_el2; + u64 guest_hcr, hcr = vcpu->arch.hcr_el2; if (!vcpu_has_nv(vcpu)) return hcr; @@ -68,10 +67,21 @@ static u64 __compute_hcr(struct kvm_vcpu *vcpu) if (!vcpu_el2_e2h_is_set(vcpu)) hcr |= HCR_NV1; + /* + * Nothing in HCR_EL2 should impact running in hypervisor + * context, apart from bits we have defined as RESx (E2H, + * HCD and co), or that cannot be set directly (the EXCLUDE + * bits). Given that we OR the guest's view with the host's, + * we can use the 0 value as the starting point, and only + * use the config-driven RES1 bits. + */ + guest_hcr = kvm_vcpu_apply_reg_masks(vcpu, HCR_EL2, 0); + write_sysreg_s(vcpu->arch.ctxt.vncr_array, SYS_VNCR_EL2); } else { host_data_clear_flag(VCPU_IN_HYP_CONTEXT); + guest_hcr = __vcpu_sys_reg(vcpu, HCR_EL2); if (guest_hcr & HCR_NV) { u64 va = __fix_to_virt(vncr_fixmap(smp_processor_id()));

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FAILED: patch "[PATCH] KVM: arm64: Filter out HCR_EL2 bits when running in" failed to apply to 6.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.15.y git checkout FETCH_HEAD git cherry-pick -x 303084ad12767db64c84ba8fcd0450aec38c8534 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081258-convent-unscrew-2e57@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 303084ad12767db64c84ba8fcd0450aec38c8534 Mon Sep 17 00:00:00 2001 From: Marc Zyngier <maz(a)kernel.org> Date: Mon, 21 Jul 2025 11:19:50 +0100 Subject: [PATCH] KVM: arm64: Filter out HCR_EL2 bits when running in hypervisor context Most HCR_EL2 bits are not supposed to affect EL2 at all, but only the guest. However, we gladly merge these bits with the host's HCR_EL2 configuration, irrespective of entering L1 or L2. This leads to some funky behaviour, such as L1 trying to inject a virtual SError for L2, and getting a taste of its own medecine. Not quite what the architecture anticipated. In the end, the only bits that matter are those we have defined as invariants, either because we've made them RESx (E2H, HCD...), or that we actively refuse to merge because the mess with KVM's own logic. Use the sanitisation infrastructure to get the RES1 bits, and let things rip in a safer way. Fixes: 04ab519bb86df ("KVM: arm64: nv: Configure HCR_EL2 for FEAT_NV2") Signed-off-by: Marc Zyngier <maz(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20250721101955.535159-3-maz@kernel.org Signed-off-by: Oliver Upton <oliver.upton(a)linux.dev> diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c index 477f1580ffea..e482181c6632 100644 --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -48,8 +48,7 @@ DEFINE_PER_CPU(unsigned long, kvm_hyp_vector); static u64 __compute_hcr(struct kvm_vcpu *vcpu) { - u64 guest_hcr = __vcpu_sys_reg(vcpu, HCR_EL2); - u64 hcr = vcpu->arch.hcr_el2; + u64 guest_hcr, hcr = vcpu->arch.hcr_el2; if (!vcpu_has_nv(vcpu)) return hcr; @@ -68,10 +67,21 @@ static u64 __compute_hcr(struct kvm_vcpu *vcpu) if (!vcpu_el2_e2h_is_set(vcpu)) hcr |= HCR_NV1; + /* + * Nothing in HCR_EL2 should impact running in hypervisor + * context, apart from bits we have defined as RESx (E2H, + * HCD and co), or that cannot be set directly (the EXCLUDE + * bits). Given that we OR the guest's view with the host's, + * we can use the 0 value as the starting point, and only + * use the config-driven RES1 bits. + */ + guest_hcr = kvm_vcpu_apply_reg_masks(vcpu, HCR_EL2, 0); + write_sysreg_s(vcpu->arch.ctxt.vncr_array, SYS_VNCR_EL2); } else { host_data_clear_flag(VCPU_IN_HYP_CONTEXT); + guest_hcr = __vcpu_sys_reg(vcpu, HCR_EL2); if (guest_hcr & HCR_NV) { u64 va = __fix_to_virt(vncr_fixmap(smp_processor_id()));

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FAILED: patch "[PATCH] KVM: arm64: Check for SYSREGS_ON_CPU before accessing the CPU" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x c6e35dff58d348c1a9489e9b3b62b3721e62631d # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081254-rejoicing-peroxide-4695@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From c6e35dff58d348c1a9489e9b3b62b3721e62631d Mon Sep 17 00:00:00 2001 From: Marc Zyngier <maz(a)kernel.org> Date: Sun, 20 Jul 2025 11:22:29 +0100 Subject: [PATCH] KVM: arm64: Check for SYSREGS_ON_CPU before accessing the CPU state Mark Brown reports that since we commit to making exceptions visible without the vcpu being loaded, the external abort selftest fails. Upon investigation, it turns out that the code that makes registers affected by an exception visible to the guest is completely broken on VHE, as we don't check whether the system registers are loaded on the CPU at this point. We managed to get away with this so far, but that's obviously as bad as it gets, Add the required checksm and document the absolute need to check for the SYSREGS_ON_CPU flag before calling into any of the __vcpu_write_sys_reg_to_cpu()__vcpu_read_sys_reg_from_cpu() helpers. Reported-by: Mark Brown <broonie(a)kernel.org> Signed-off-by: Marc Zyngier <maz(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/18535df8-e647-4643-af9a-bb780af03a70@sirena.org.uk Link: https://lore.kernel.org/r/20250720102229.179114-1-maz@kernel.org Signed-off-by: Oliver Upton <oliver.upton(a)linux.dev> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index e54d29feb469..d373d555a69b 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -1169,6 +1169,8 @@ static inline bool __vcpu_read_sys_reg_from_cpu(int reg, u64 *val) * System registers listed in the switch are not saved on every * exit from the guest but are only saved on vcpu_put. * + * SYSREGS_ON_CPU *MUST* be checked before using this helper. + * * Note that MPIDR_EL1 for the guest is set by KVM via VMPIDR_EL2 but * should never be listed below, because the guest cannot modify its * own MPIDR_EL1 and MPIDR_EL1 is accessed for VCPU A from VCPU B's @@ -1221,6 +1223,8 @@ static inline bool __vcpu_write_sys_reg_to_cpu(u64 val, int reg) * System registers listed in the switch are not restored on every * entry to the guest but are only restored on vcpu_load. * + * SYSREGS_ON_CPU *MUST* be checked before using this helper. + * * Note that MPIDR_EL1 for the guest is set by KVM via VMPIDR_EL2 but * should never be listed below, because the MPIDR should only be set * once, before running the VCPU, and never changed later. diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c index 7dafd10e52e8..95d186e0bf54 100644 --- a/arch/arm64/kvm/hyp/exception.c +++ b/arch/arm64/kvm/hyp/exception.c @@ -26,7 +26,8 @@ static inline u64 __vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg) if (unlikely(vcpu_has_nv(vcpu))) return vcpu_read_sys_reg(vcpu, reg); - else if (__vcpu_read_sys_reg_from_cpu(reg, &val)) + else if (vcpu_get_flag(vcpu, SYSREGS_ON_CPU) && + __vcpu_read_sys_reg_from_cpu(reg, &val)) return val; return __vcpu_sys_reg(vcpu, reg); @@ -36,7 +37,8 @@ static inline void __vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) { if (unlikely(vcpu_has_nv(vcpu))) vcpu_write_sys_reg(vcpu, val, reg); - else if (!__vcpu_write_sys_reg_to_cpu(val, reg)) + else if (!vcpu_get_flag(vcpu, SYSREGS_ON_CPU) || + !__vcpu_write_sys_reg_to_cpu(val, reg)) __vcpu_assign_sys_reg(vcpu, reg, val); }

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FAILED: patch "[PATCH] KVM: arm64: Check for SYSREGS_ON_CPU before accessing the CPU" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x c6e35dff58d348c1a9489e9b3b62b3721e62631d # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081253-shrunk-karate-ad70@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From c6e35dff58d348c1a9489e9b3b62b3721e62631d Mon Sep 17 00:00:00 2001 From: Marc Zyngier <maz(a)kernel.org> Date: Sun, 20 Jul 2025 11:22:29 +0100 Subject: [PATCH] KVM: arm64: Check for SYSREGS_ON_CPU before accessing the CPU state Mark Brown reports that since we commit to making exceptions visible without the vcpu being loaded, the external abort selftest fails. Upon investigation, it turns out that the code that makes registers affected by an exception visible to the guest is completely broken on VHE, as we don't check whether the system registers are loaded on the CPU at this point. We managed to get away with this so far, but that's obviously as bad as it gets, Add the required checksm and document the absolute need to check for the SYSREGS_ON_CPU flag before calling into any of the __vcpu_write_sys_reg_to_cpu()__vcpu_read_sys_reg_from_cpu() helpers. Reported-by: Mark Brown <broonie(a)kernel.org> Signed-off-by: Marc Zyngier <maz(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/18535df8-e647-4643-af9a-bb780af03a70@sirena.org.uk Link: https://lore.kernel.org/r/20250720102229.179114-1-maz@kernel.org Signed-off-by: Oliver Upton <oliver.upton(a)linux.dev> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index e54d29feb469..d373d555a69b 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -1169,6 +1169,8 @@ static inline bool __vcpu_read_sys_reg_from_cpu(int reg, u64 *val) * System registers listed in the switch are not saved on every * exit from the guest but are only saved on vcpu_put. * + * SYSREGS_ON_CPU *MUST* be checked before using this helper. + * * Note that MPIDR_EL1 for the guest is set by KVM via VMPIDR_EL2 but * should never be listed below, because the guest cannot modify its * own MPIDR_EL1 and MPIDR_EL1 is accessed for VCPU A from VCPU B's @@ -1221,6 +1223,8 @@ static inline bool __vcpu_write_sys_reg_to_cpu(u64 val, int reg) * System registers listed in the switch are not restored on every * entry to the guest but are only restored on vcpu_load. * + * SYSREGS_ON_CPU *MUST* be checked before using this helper. + * * Note that MPIDR_EL1 for the guest is set by KVM via VMPIDR_EL2 but * should never be listed below, because the MPIDR should only be set * once, before running the VCPU, and never changed later. diff --git a/arch/arm64/kvm/hyp/exception.c b/arch/arm64/kvm/hyp/exception.c index 7dafd10e52e8..95d186e0bf54 100644 --- a/arch/arm64/kvm/hyp/exception.c +++ b/arch/arm64/kvm/hyp/exception.c @@ -26,7 +26,8 @@ static inline u64 __vcpu_read_sys_reg(const struct kvm_vcpu *vcpu, int reg) if (unlikely(vcpu_has_nv(vcpu))) return vcpu_read_sys_reg(vcpu, reg); - else if (__vcpu_read_sys_reg_from_cpu(reg, &val)) + else if (vcpu_get_flag(vcpu, SYSREGS_ON_CPU) && + __vcpu_read_sys_reg_from_cpu(reg, &val)) return val; return __vcpu_sys_reg(vcpu, reg); @@ -36,7 +37,8 @@ static inline void __vcpu_write_sys_reg(struct kvm_vcpu *vcpu, u64 val, int reg) { if (unlikely(vcpu_has_nv(vcpu))) vcpu_write_sys_reg(vcpu, val, reg); - else if (!__vcpu_write_sys_reg_to_cpu(val, reg)) + else if (!vcpu_get_flag(vcpu, SYSREGS_ON_CPU) || + !__vcpu_write_sys_reg_to_cpu(val, reg)) __vcpu_assign_sys_reg(vcpu, reg, val); }

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FAILED: patch "[PATCH] KVM: VMX: Allow guest to set DEBUGCTL.RTM_DEBUG if RTM is" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 17ec2f965344ee3fd6620bef7ef68792f4ac3af0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081206-eclipse-preview-8baf@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 17ec2f965344ee3fd6620bef7ef68792f4ac3af0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Tue, 10 Jun 2025 16:20:06 -0700 Subject: [PATCH] KVM: VMX: Allow guest to set DEBUGCTL.RTM_DEBUG if RTM is supported Let the guest set DEBUGCTL.RTM_DEBUG if RTM is supported according to the guest CPUID model, as debug support is supposed to be available if RTM is supported, and there are no known downsides to letting the guest debug RTM aborts. Note, there are no known bug reports related to RTM_DEBUG, the primary motivation is to reduce the probability of breaking existing guests when a future change adds a missing consistency check on vmcs12.GUEST_DEBUGCTL (KVM currently lets L2 run with whatever hardware supports; whoops). Note #2, KVM already emulates DR6.RTM, and doesn't restrict access to DR7.RTM. Fixes: 83c529151ab0 ("KVM: x86: expose Intel cpu new features (HLE, RTM) to guest") Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20250610232010.162191-5-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index b7dded3c8113..fa878b136eba 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -419,6 +419,7 @@ #define DEBUGCTLMSR_FREEZE_PERFMON_ON_PMI (1UL << 12) #define DEBUGCTLMSR_FREEZE_IN_SMM_BIT 14 #define DEBUGCTLMSR_FREEZE_IN_SMM (1UL << DEBUGCTLMSR_FREEZE_IN_SMM_BIT) +#define DEBUGCTLMSR_RTM_DEBUG BIT(15) #define MSR_PEBS_FRONTEND 0x000003f7 diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 4ee6cc796855..311f6fa53b67 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2186,6 +2186,10 @@ static u64 vmx_get_supported_debugctl(struct kvm_vcpu *vcpu, bool host_initiated (host_initiated || intel_pmu_lbr_is_enabled(vcpu))) debugctl |= DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI; + if (boot_cpu_has(X86_FEATURE_RTM) && + (host_initiated || guest_cpu_cap_has(vcpu, X86_FEATURE_RTM))) + debugctl |= DEBUGCTLMSR_RTM_DEBUG; + return debugctl; }

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FAILED: patch "[PATCH] KVM: VMX: Allow guest to set DEBUGCTL.RTM_DEBUG if RTM is" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 17ec2f965344ee3fd6620bef7ef68792f4ac3af0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081205-resurface-filler-e78b@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 17ec2f965344ee3fd6620bef7ef68792f4ac3af0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Tue, 10 Jun 2025 16:20:06 -0700 Subject: [PATCH] KVM: VMX: Allow guest to set DEBUGCTL.RTM_DEBUG if RTM is supported Let the guest set DEBUGCTL.RTM_DEBUG if RTM is supported according to the guest CPUID model, as debug support is supposed to be available if RTM is supported, and there are no known downsides to letting the guest debug RTM aborts. Note, there are no known bug reports related to RTM_DEBUG, the primary motivation is to reduce the probability of breaking existing guests when a future change adds a missing consistency check on vmcs12.GUEST_DEBUGCTL (KVM currently lets L2 run with whatever hardware supports; whoops). Note #2, KVM already emulates DR6.RTM, and doesn't restrict access to DR7.RTM. Fixes: 83c529151ab0 ("KVM: x86: expose Intel cpu new features (HLE, RTM) to guest") Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20250610232010.162191-5-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index b7dded3c8113..fa878b136eba 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -419,6 +419,7 @@ #define DEBUGCTLMSR_FREEZE_PERFMON_ON_PMI (1UL << 12) #define DEBUGCTLMSR_FREEZE_IN_SMM_BIT 14 #define DEBUGCTLMSR_FREEZE_IN_SMM (1UL << DEBUGCTLMSR_FREEZE_IN_SMM_BIT) +#define DEBUGCTLMSR_RTM_DEBUG BIT(15) #define MSR_PEBS_FRONTEND 0x000003f7 diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 4ee6cc796855..311f6fa53b67 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2186,6 +2186,10 @@ static u64 vmx_get_supported_debugctl(struct kvm_vcpu *vcpu, bool host_initiated (host_initiated || intel_pmu_lbr_is_enabled(vcpu))) debugctl |= DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI; + if (boot_cpu_has(X86_FEATURE_RTM) && + (host_initiated || guest_cpu_cap_has(vcpu, X86_FEATURE_RTM))) + debugctl |= DEBUGCTLMSR_RTM_DEBUG; + return debugctl; }

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FAILED: patch "[PATCH] KVM: x86: Drop kvm_x86_ops.set_dr6() in favor of a new" failed to apply to 6.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.15.y git checkout FETCH_HEAD git cherry-pick -x 80c64c7afea1da6a93ebe88d3d29d8a60377ef80 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081242-polygon-exploring-2a87@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 80c64c7afea1da6a93ebe88d3d29d8a60377ef80 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc(a)google.com> Date: Tue, 10 Jun 2025 16:20:05 -0700 Subject: [PATCH] KVM: x86: Drop kvm_x86_ops.set_dr6() in favor of a new KVM_RUN flag Instruct vendor code to load the guest's DR6 into hardware via a new KVM_RUN flag, and remove kvm_x86_ops.set_dr6(), whose sole purpose was to load vcpu->arch.dr6 into hardware when DR6 can be read/written directly by the guest. Note, TDX already WARNs on any run_flag being set, i.e. will yell if KVM thinks DR6 needs to be reloaded. TDX vCPUs force KVM_DEBUGREG_AUTO_SWITCH and never clear the flag, i.e. should never observe KVM_RUN_LOAD_GUEST_DR6. Cc: stable(a)vger.kernel.org Link: https://lore.kernel.org/r/20250610232010.162191-4-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc(a)google.com> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h index 8d50e3e0a19b..9e0c37ea267e 100644 --- a/arch/x86/include/asm/kvm-x86-ops.h +++ b/arch/x86/include/asm/kvm-x86-ops.h @@ -49,7 +49,6 @@ KVM_X86_OP(set_idt) KVM_X86_OP(get_gdt) KVM_X86_OP(set_gdt) KVM_X86_OP(sync_dirty_debug_regs) -KVM_X86_OP(set_dr6) KVM_X86_OP(set_dr7) KVM_X86_OP(cache_reg) KVM_X86_OP(get_rflags) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 8d81684fa15d..4f7ee2dbf10e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1676,6 +1676,7 @@ static inline u16 kvm_lapic_irq_dest_mode(bool dest_mode_logical) enum kvm_x86_run_flags { KVM_RUN_FORCE_IMMEDIATE_EXIT = BIT(0), + KVM_RUN_LOAD_GUEST_DR6 = BIT(1), }; struct kvm_x86_ops { @@ -1728,7 +1729,6 @@ struct kvm_x86_ops { void (*get_gdt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt); void (*set_gdt)(struct kvm_vcpu *vcpu, struct desc_ptr *dt); void (*sync_dirty_debug_regs)(struct kvm_vcpu *vcpu); - void (*set_dr6)(struct kvm_vcpu *vcpu, unsigned long value); void (*set_dr7)(struct kvm_vcpu *vcpu, unsigned long value); void (*cache_reg)(struct kvm_vcpu *vcpu, enum kvm_reg reg); unsigned long (*get_rflags)(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 83d1b62130b1..be8c43049f4d 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4438,10 +4438,13 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) svm_hv_update_vp_id(svm->vmcb, vcpu); /* - * Run with all-zero DR6 unless needed, so that we can get the exact cause - * of a #DB. + * Run with all-zero DR6 unless the guest can write DR6 freely, so that + * KVM can get the exact cause of a #DB. Note, loading guest DR6 from + * KVM's snapshot is only necessary when DR accesses won't exit. */ - if (likely(!(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT))) + if (unlikely(run_flags & KVM_RUN_LOAD_GUEST_DR6)) + svm_set_dr6(vcpu, vcpu->arch.dr6); + else if (likely(!(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT))) svm_set_dr6(vcpu, DR6_ACTIVE_LOW); clgi(); @@ -5252,7 +5255,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .set_idt = svm_set_idt, .get_gdt = svm_get_gdt, .set_gdt = svm_set_gdt, - .set_dr6 = svm_set_dr6, .set_dr7 = svm_set_dr7, .sync_dirty_debug_regs = svm_sync_dirty_debug_regs, .cache_reg = svm_cache_reg, diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c index fef3e3803707..c85cbce6d2f6 100644 --- a/arch/x86/kvm/vmx/main.c +++ b/arch/x86/kvm/vmx/main.c @@ -489,14 +489,6 @@ static void vt_set_gdt(struct kvm_vcpu *vcpu, struct desc_ptr *dt) vmx_set_gdt(vcpu, dt); } -static void vt_set_dr6(struct kvm_vcpu *vcpu, unsigned long val) -{ - if (is_td_vcpu(vcpu)) - return; - - vmx_set_dr6(vcpu, val); -} - static void vt_set_dr7(struct kvm_vcpu *vcpu, unsigned long val) { if (is_td_vcpu(vcpu)) @@ -943,7 +935,6 @@ struct kvm_x86_ops vt_x86_ops __initdata = { .set_idt = vt_op(set_idt), .get_gdt = vt_op(get_gdt), .set_gdt = vt_op(set_gdt), - .set_dr6 = vt_op(set_dr6), .set_dr7 = vt_op(set_dr7), .sync_dirty_debug_regs = vt_op(sync_dirty_debug_regs), .cache_reg = vt_op(cache_reg), diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index a61a28944de6..4ee6cc796855 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5606,12 +5606,6 @@ void vmx_sync_dirty_debug_regs(struct kvm_vcpu *vcpu) set_debugreg(DR6_RESERVED, 6); } -void vmx_set_dr6(struct kvm_vcpu *vcpu, unsigned long val) -{ - lockdep_assert_irqs_disabled(); - set_debugreg(vcpu->arch.dr6, 6); -} - void vmx_set_dr7(struct kvm_vcpu *vcpu, unsigned long val) { vmcs_writel(GUEST_DR7, val); @@ -7370,6 +7364,9 @@ fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]); vcpu->arch.regs_dirty = 0; + if (run_flags & KVM_RUN_LOAD_GUEST_DR6) + set_debugreg(vcpu->arch.dr6, 6); + /* * Refresh vmcs.HOST_CR3 if necessary. This must be done immediately * prior to VM-Enter, as the kernel may load a new ASID (PCID) any time diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 07ff02eed399..7fe3549bbd93 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11046,7 +11046,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) set_debugreg(vcpu->arch.eff_db[3], 3); /* When KVM_DEBUGREG_WONT_EXIT, dr6 is accessible in guest. */ if (unlikely(vcpu->arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT)) - kvm_x86_call(set_dr6)(vcpu, vcpu->arch.dr6); + run_flags |= KVM_RUN_LOAD_GUEST_DR6; } else if (unlikely(hw_breakpoint_active())) { set_debugreg(0, 7); }

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FAILED: patch "[PATCH] net: usbnet: Fix the wrong netif_carrier_on() call" failed to apply to 5.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 8466d393700f9ccef68134d3349f4e0a087679b9 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081206-rejoicing-democrat-be9e@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From 8466d393700f9ccef68134d3349f4e0a087679b9 Mon Sep 17 00:00:00 2001 From: Ammar Faizi <ammarfaizi2(a)gnuweeb.org> Date: Wed, 6 Aug 2025 07:31:05 +0700 Subject: [PATCH] net: usbnet: Fix the wrong netif_carrier_on() call The commit referenced in the Fixes tag causes usbnet to malfunction (identified via git bisect). Post-commit, my external RJ45 LAN cable fails to connect. Linus also reported the same issue after pulling that commit. The code has a logic error: netif_carrier_on() is only called when the link is already on. Fix this by moving the netif_carrier_on() call outside the if-statement entirely. This ensures it is always called when EVENT_LINK_CARRIER_ON is set and properly clears it regardless of the link state. Cc: stable(a)vger.kernel.org Cc: Armando Budianto <sprite(a)gnuweeb.org> Reviewed-by: Simon Horman <horms(a)kernel.org> Suggested-by: Linus Torvalds <torvalds(a)linux-foundation.org> Link: https://lore.kernel.org/all/CAHk-=wjqL4uF0MG_c8+xHX1Vv8==sPYQrtzbdA3kzi9628… Closes: https://lore.kernel.org/netdev/CAHk-=wjKh8X4PT_mU1kD4GQrbjivMfPn-_hXa6han_B… Closes: https://lore.kernel.org/netdev/0752dee6-43d6-4e1f-81d2-4248142cccd2@gnuweeb… Fixes: 0d9cfc9b8cb1 ("net: usbnet: Avoid potential RCU stall on LINK_CHANGE event") Signed-off-by: Ammar Faizi <ammarfaizi2(a)gnuweeb.org> Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index a38ffbf4b3f0..511c4154cf74 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -1120,6 +1120,9 @@ static void __handle_link_change(struct usbnet *dev) if (!test_bit(EVENT_DEV_OPEN, &dev->flags)) return; + if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags)) + netif_carrier_on(dev->net); + if (!netif_carrier_ok(dev->net)) { /* kill URBs for reading packets to save bus bandwidth */ unlink_urbs(dev, &dev->rxq); @@ -1129,9 +1132,6 @@ static void __handle_link_change(struct usbnet *dev) * tx queue is stopped by netcore after link becomes off */ } else { - if (test_and_clear_bit(EVENT_LINK_CARRIER_ON, &dev->flags)) - netif_carrier_on(dev->net); - /* submitting URBs for reading packets */ queue_work(system_bh_wq, &dev->bh_work); }

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