On Sun, 2023-07-23 at 22:41 +0200, gregkh@xxxxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx>. 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@xxxxxxxxxxxxxxx>' --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@xxxxxxxxxx> > 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@xxxxxxxxxxxxxxx > Fixes: 8e01d9a396e6 ("KVM: arm64: vgic-v4: Move the GICv4 residency flow to be driven by vcpu_load/put") > Reported-by: Xiang Chen <chenxiang66@xxxxxxxxxxxxx> > Suggested-by: Zenghui Yu <yuzenghui@xxxxxxxxxx> > Tested-by: Xiang Chen <chenxiang66@xxxxxxxxxxxxx> > Co-developed-by: Oliver Upton <oliver.upton@xxxxxxxxx> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > Acked-by: Zenghui Yu <yuzenghui@xxxxxxxxxx> > Link: https://lore.kernel.org/r/20230713070657.3873244-1-maz@xxxxxxxxxx > Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx> > > 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); >
