On Sun, 2023-07-23 at 22:41 +0200, gregkh@linuxfoundation.org wrote:
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@vger.kernel.org.
Blast from the past, but we've recently been bitten by this bug when running a v5.10 kernel. I'm going to back-port it to v5.10 and v5.15, resolve the conflicts and post it.
Marc, please will you take a look and see if you're happy with the backport? The main change is going back to the old style of vCPU flag manipulation.
JG
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 b321c31c9b7b309dcde5e8854b741c8e6a9a05f0 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023072324-aviation-delirious-b27d@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
b321c31c9b7b ("KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t preemption") 0c2f9acf6ae7 ("KVM: arm64: PMU: Don't overwrite PMUSERENR with vcpu loaded") 8681f7175901 ("KVM: arm64: PMU: Restore the host's PMUSERENR_EL0") 009d6dc87a56 ("ARM: perf: Allow the use of the PMUv3 driver on 32bit ARM") 711432770f78 ("perf: pmuv3: Abstract PMU version checks") df29ddf4f04b ("arm64: perf: Abstract system register accesses away") 7755cec63ade ("arm64: perf: Move PMUv3 driver to drivers/perf") cc91b9481605 ("arm64/perf: Replace PMU version number '0' with ID_AA64DFR0_EL1_PMUVer_NI") 4151bb636acf ("KVM: arm64: Fix SMPRI_EL1/TPIDR2_EL0 trapping on VHE") bb0cca240a16 ("Merge branch kvm-arm64/single-step-async-exception into kvmarm-master/next")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b321c31c9b7b309dcde5e8854b741c8e6a9a05f0 Mon Sep 17 00:00:00 2001
From: Marc Zyngier maz@kernel.org Date: Thu, 13 Jul 2023 08:06:57 +0100 Subject: [PATCH] KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t preemption
Xiang reports that VMs occasionally fail to boot on GICv4.1 systems when running a preemptible kernel, as it is possible that a vCPU is blocked without requesting a doorbell interrupt.
The issue is that any preemption that occurs between vgic_v4_put() and schedule() on the block path will mark the vPE as nonresident and *not* request a doorbell irq. This occurs because when the vcpu thread is resumed on its way to block, vcpu_load() will make the vPE resident again. Once the vcpu actually blocks, we don't request a doorbell anymore, and the vcpu won't be woken up on interrupt delivery.
Fix it by tracking that we're entering WFI, and key the doorbell request on that flag. This allows us not to make the vPE resident when going through a preempt/schedule cycle, meaning we don't lose any state.
Cc: stable@vger.kernel.org Fixes: 8e01d9a396e6 ("KVM: arm64: vgic-v4: Move the GICv4 residency flow to be driven by vcpu_load/put") Reported-by: Xiang Chen chenxiang66@hisilicon.com Suggested-by: Zenghui Yu yuzenghui@huawei.com Tested-by: Xiang Chen chenxiang66@hisilicon.com Co-developed-by: Oliver Upton oliver.upton@linux.dev Signed-off-by: Marc Zyngier maz@kernel.org Acked-by: Zenghui Yu yuzenghui@huawei.com Link: https://lore.kernel.org/r/20230713070657.3873244-1-maz@kernel.org Signed-off-by: Oliver Upton oliver.upton@linux.dev
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 8b6096753740..d3dd05bbfe23 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -727,6 +727,8 @@ struct kvm_vcpu_arch { #define DBG_SS_ACTIVE_PENDING __vcpu_single_flag(sflags, BIT(5)) /* PMUSERENR for the guest EL0 is on physical CPU */ #define PMUSERENR_ON_CPU __vcpu_single_flag(sflags, BIT(6)) +/* WFI instruction trapped */ +#define IN_WFI __vcpu_single_flag(sflags, BIT(7)) /* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index a402ea5511f3..72dc53a75d1c 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -718,13 +718,15 @@ void kvm_vcpu_wfi(struct kvm_vcpu *vcpu) */ preempt_disable(); kvm_vgic_vmcr_sync(vcpu);
- vgic_v4_put(vcpu, true);
- vcpu_set_flag(vcpu, IN_WFI);
- vgic_v4_put(vcpu); preempt_enable();
kvm_vcpu_halt(vcpu); vcpu_clear_flag(vcpu, IN_WFIT); preempt_disable();
- vcpu_clear_flag(vcpu, IN_WFI); vgic_v4_load(vcpu); preempt_enable();
} @@ -792,7 +794,7 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu) if (kvm_check_request(KVM_REQ_RELOAD_GICv4, vcpu)) { /* The distributor enable bits were changed */ preempt_disable();
vgic_v4_put(vcpu, false);
vgic_v4_put(vcpu); vgic_v4_load(vcpu); preempt_enable();diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c index c3b8e132d599..3dfc8b84e03e 100644 --- a/arch/arm64/kvm/vgic/vgic-v3.c +++ b/arch/arm64/kvm/vgic/vgic-v3.c @@ -749,7 +749,7 @@ void vgic_v3_put(struct kvm_vcpu *vcpu) { struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
- WARN_ON(vgic_v4_put(vcpu, false));
- WARN_ON(vgic_v4_put(vcpu));
vgic_v3_vmcr_sync(vcpu); diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c index c1c28fe680ba..339a55194b2c 100644 --- a/arch/arm64/kvm/vgic/vgic-v4.c +++ b/arch/arm64/kvm/vgic/vgic-v4.c @@ -336,14 +336,14 @@ void vgic_v4_teardown(struct kvm *kvm) its_vm->vpes = NULL; } -int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db) +int vgic_v4_put(struct kvm_vcpu *vcpu) { struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; if (!vgic_supports_direct_msis(vcpu->kvm) || !vpe->resident) return 0;
- return its_make_vpe_non_resident(vpe, need_db);
- return its_make_vpe_non_resident(vpe, !!vcpu_get_flag(vcpu, IN_WFI));
} int vgic_v4_load(struct kvm_vcpu *vcpu) @@ -354,6 +354,9 @@ int vgic_v4_load(struct kvm_vcpu *vcpu) if (!vgic_supports_direct_msis(vcpu->kvm) || vpe->resident) return 0;
- if (vcpu_get_flag(vcpu, IN_WFI))
return 0;- /*
- Before making the VPE resident, make sure the redistributor
- corresponding to our current CPU expects us here. See the
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h index 402b545959af..5b27f94d4fad 100644 --- a/include/kvm/arm_vgic.h +++ b/include/kvm/arm_vgic.h @@ -431,7 +431,7 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq, int vgic_v4_load(struct kvm_vcpu *vcpu); void vgic_v4_commit(struct kvm_vcpu *vcpu); -int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db); +int vgic_v4_put(struct kvm_vcpu *vcpu); /* CPU HP callbacks */ void kvm_vgic_cpu_up(void);