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@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 2478b1b220c49d25cb1c3f061ec4f9b351d9a131 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025081228-outthink-finisher-2a2a@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2478b1b220c49d25cb1c3f061ec4f9b351d9a131 Mon Sep 17 00:00:00 2001 From: Sean Christopherson seanjc@google.com Date: Tue, 10 Jun 2025 16:20:04 -0700 Subject: [PATCH] KVM: x86: Convert vcpu_run()'s immediate exit param into a generic bitmap

Convert kvm_x86_ops.vcpu_run()'s "force_immediate_exit" boolean parameter into an a generic bitmap so that similar "take action" information can be passed to vendor code without creating a pile of boolean parameters.

This will allow dropping kvm_x86_ops.set_dr6() in favor of a new flag, and will also allow for adding similar functionality for re-loading debugctl in the active VMCS.

Opportunistically massage the TDX WARN and comment to prepare for adding more run_flags, all of which are expected to be mutually exclusive with TDX, i.e. should be WARNed on.

No functional change intended.

Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250610232010.162191-3-seanjc@google.com Signed-off-by: Sean Christopherson seanjc@google.com

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index b4a391929cdb..8d81684fa15d 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1674,6 +1674,10 @@ static inline u16 kvm_lapic_irq_dest_mode(bool dest_mode_logical) return dest_mode_logical ? APIC_DEST_LOGICAL : APIC_DEST_PHYSICAL; }

+enum kvm_x86_run_flags { + KVM_RUN_FORCE_IMMEDIATE_EXIT = BIT(0), +}; + struct kvm_x86_ops { const char *name;

@@ -1755,7 +1759,7 @@ struct kvm_x86_ops {

int (*vcpu_pre_run)(struct kvm_vcpu *vcpu); enum exit_fastpath_completion (*vcpu_run)(struct kvm_vcpu *vcpu, - bool force_immediate_exit); + u64 run_flags); int (*handle_exit)(struct kvm_vcpu *vcpu, enum exit_fastpath_completion exit_fastpath); int (*skip_emulated_instruction)(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index ab9b947dbf4f..83d1b62130b1 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4389,9 +4389,9 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu, bool spec_ctrl_in guest_state_exit_irqoff(); }

-static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu, - bool force_immediate_exit) +static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) { + bool force_immediate_exit = run_flags & KVM_RUN_FORCE_IMMEDIATE_EXIT; struct vcpu_svm *svm = to_svm(vcpu); bool spec_ctrl_intercepted = msr_write_intercepted(vcpu, MSR_IA32_SPEC_CTRL);

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c index d1e02e567b57..fef3e3803707 100644 --- a/arch/x86/kvm/vmx/main.c +++ b/arch/x86/kvm/vmx/main.c @@ -175,12 +175,12 @@ static int vt_vcpu_pre_run(struct kvm_vcpu *vcpu) return vmx_vcpu_pre_run(vcpu); }

-static fastpath_t vt_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit) +static fastpath_t vt_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) { if (is_td_vcpu(vcpu)) - return tdx_vcpu_run(vcpu, force_immediate_exit); + return tdx_vcpu_run(vcpu, run_flags);

- return vmx_vcpu_run(vcpu, force_immediate_exit); + return vmx_vcpu_run(vcpu, run_flags); }

static int vt_handle_exit(struct kvm_vcpu *vcpu, diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index 4d2426ab6747..1c4b4d9a1acb 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -1025,20 +1025,20 @@ static void tdx_load_host_xsave_state(struct kvm_vcpu *vcpu) DEBUGCTLMSR_FREEZE_PERFMON_ON_PMI | \ DEBUGCTLMSR_FREEZE_IN_SMM)

-fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit) +fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) { struct vcpu_tdx *tdx = to_tdx(vcpu); struct vcpu_vt *vt = to_vt(vcpu);

/* - * force_immediate_exit requires vCPU entering for events injection with - * an immediately exit followed. But The TDX module doesn't guarantee - * entry, it's already possible for KVM to _think_ it completely entry - * to the guest without actually having done so. - * Since KVM never needs to force an immediate exit for TDX, and can't - * do direct injection, just warn on force_immediate_exit. + * WARN if KVM wants to force an immediate exit, as the TDX module does + * not guarantee entry into the guest, i.e. it's possible for KVM to + * _think_ it completed entry to the guest and forced an immediate exit + * without actually having done so. Luckily, KVM never needs to force + * an immediate exit for TDX (KVM can't do direct event injection, so + * just WARN and continue on. */ - WARN_ON_ONCE(force_immediate_exit); + WARN_ON_ONCE(run_flags);

/* * Wait until retry of SEPT-zap-related SEAMCALL completes before @@ -1048,7 +1048,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit) if (unlikely(READ_ONCE(to_kvm_tdx(vcpu->kvm)->wait_for_sept_zap))) return EXIT_FASTPATH_EXIT_HANDLED;

- trace_kvm_entry(vcpu, force_immediate_exit); + trace_kvm_entry(vcpu, run_flags & KVM_RUN_FORCE_IMMEDIATE_EXIT);

if (pi_test_on(&vt->pi_desc)) { apic->send_IPI_self(POSTED_INTR_VECTOR); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 4953846cb30d..a61a28944de6 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7323,8 +7323,9 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu, guest_state_exit_irqoff(); }

-fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit) +fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags) { + bool force_immediate_exit = run_flags & KVM_RUN_FORCE_IMMEDIATE_EXIT; struct vcpu_vmx *vmx = to_vmx(vcpu); unsigned long cr3, cr4;

diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h index b4596f651232..0b4f5c5558d0 100644 --- a/arch/x86/kvm/vmx/x86_ops.h +++ b/arch/x86/kvm/vmx/x86_ops.h @@ -21,7 +21,7 @@ void vmx_vm_destroy(struct kvm *kvm); int vmx_vcpu_precreate(struct kvm *kvm); int vmx_vcpu_create(struct kvm_vcpu *vcpu); int vmx_vcpu_pre_run(struct kvm_vcpu *vcpu); -fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit); +fastpath_t vmx_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags); void vmx_vcpu_free(struct kvm_vcpu *vcpu); void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event); void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu); @@ -133,7 +133,7 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event); void tdx_vcpu_free(struct kvm_vcpu *vcpu); void tdx_vcpu_load(struct kvm_vcpu *vcpu, int cpu); int tdx_vcpu_pre_run(struct kvm_vcpu *vcpu); -fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit); +fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, u64 run_flags); void tdx_prepare_switch_to_guest(struct kvm_vcpu *vcpu); void tdx_vcpu_put(struct kvm_vcpu *vcpu); bool tdx_protected_apic_has_interrupt(struct kvm_vcpu *vcpu); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b58a74c1722d..07ff02eed399 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10779,6 +10779,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) dm_request_for_irq_injection(vcpu) && kvm_cpu_accept_dm_intr(vcpu); fastpath_t exit_fastpath; + u64 run_flags;

bool req_immediate_exit = false;

@@ -11023,8 +11024,11 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) goto cancel_injection; }

- if (req_immediate_exit) + run_flags = 0; + if (req_immediate_exit) { + run_flags |= KVM_RUN_FORCE_IMMEDIATE_EXIT; kvm_make_request(KVM_REQ_EVENT, vcpu); + }

fpregs_assert_state_consistent(); if (test_thread_flag(TIF_NEED_FPU_LOAD)) @@ -11061,8 +11065,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) WARN_ON_ONCE((kvm_vcpu_apicv_activated(vcpu) != kvm_vcpu_apicv_active(vcpu)) && (kvm_get_apic_mode(vcpu) != LAPIC_MODE_DISABLED));

- exit_fastpath = kvm_x86_call(vcpu_run)(vcpu, - req_immediate_exit); + exit_fastpath = kvm_x86_call(vcpu_run)(vcpu, run_flags); if (likely(exit_fastpath != EXIT_FASTPATH_REENTER_GUEST)) break;

@@ -11074,6 +11077,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) break; }

+ run_flags = 0; + /* Note, VM-Exits that go down the "slow" path are accounted below. */ ++vcpu->stat.exits; }