FAILED: patch "[PATCH] KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t" failed to apply to 5.10-stable tree

FAILED: patch "[PATCH] KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t" failed to apply to 5.10-stable tree

[gregkh]

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>.

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);

Re: FAILED: patch "[PATCH] KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t" failed to apply to 5.10-stable tree

[Gowans, James]

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);
> 

[PATCH 5.10.y] KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t preemption

[James Gowans]

From: Marc Zyngier <maz@kernel.org>

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>

(cherry picked from commit b321c31c9b7b309dcde5e8854b741c8e6a9a05f0)

[modified to wrangle the vCPU flags directly instead of going through
the flag helper macros as they have not yet been introduced. Also doing
the flag wranging in the kvm_arch_vcpu_{un}blocking() hooks as the
introduction of kvm_vcpu_wfi has not yet happened. See:
6109c5a6ab7f ("KVM: arm64: Move vGIC v4 handling for WFI out arch callback hook")]

Signed-off-by: James Gowans <jgowans@amazon.com>
---
 arch/arm64/include/asm/kvm_host.h | 1 +
 arch/arm64/kvm/arm.c              | 6 ++++--
 arch/arm64/kvm/vgic/vgic-v3.c     | 2 +-
 arch/arm64/kvm/vgic/vgic-v4.c     | 8 ++++++--
 include/kvm/arm_vgic.h            | 2 +-
 5 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 912b83e784bb..48ee1fe3aca4 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -410,6 +410,7 @@ struct kvm_vcpu_arch {
 #define KVM_ARM64_GUEST_HAS_SVE		(1 << 5) /* SVE exposed to guest */
 #define KVM_ARM64_VCPU_SVE_FINALIZED	(1 << 6) /* SVE config completed */
 #define KVM_ARM64_GUEST_HAS_PTRAUTH	(1 << 7) /* PTRAUTH exposed to guest */
+#define KVM_ARM64_VCPU_IN_WFI		(1 << 8) /* WFI instruction trapped */
 
 #define vcpu_has_sve(vcpu) (system_supports_sve() && \
 			    ((vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_SVE))
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 4d63fcd7574b..afe8be2fef88 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -332,13 +332,15 @@ void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
 	 */
 	preempt_disable();
 	kvm_vgic_vmcr_sync(vcpu);
-	vgic_v4_put(vcpu, true);
+	vcpu->arch.flags |= KVM_ARM64_VCPU_IN_WFI;
+	vgic_v4_put(vcpu);
 	preempt_enable();
 }
 
 void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
 {
 	preempt_disable();
+	vcpu->arch.flags &= ~KVM_ARM64_VCPU_IN_WFI;
 	vgic_v4_load(vcpu);
 	preempt_enable();
 }
@@ -649,7 +651,7 @@ static void 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 9cdf39a94a63..29c12bf9601a 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -682,7 +682,7 @@ 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 b5fa73c9fd35..cdfaaeabbb7d 100644
--- a/arch/arm64/kvm/vgic/vgic-v4.c
+++ b/arch/arm64/kvm/vgic/vgic-v4.c
@@ -310,14 +310,15 @@ 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->arch.flags & KVM_ARM64_VCPU_IN_WFI);
 }
 
 int vgic_v4_load(struct kvm_vcpu *vcpu)
@@ -328,6 +329,9 @@ int vgic_v4_load(struct kvm_vcpu *vcpu)
 	if (!vgic_supports_direct_msis(vcpu->kvm) || vpe->resident)
 		return 0;
 
+	if (vcpu->arch.flags & KVM_ARM64_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 a8d8fdcd3723..92348c085c0c 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -402,6 +402,6 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq,
 				 struct kvm_kernel_irq_routing_entry *irq_entry);
 
 int vgic_v4_load(struct kvm_vcpu *vcpu);
-int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db);
+int vgic_v4_put(struct kvm_vcpu *vcpu);
 
 #endif /* __KVM_ARM_VGIC_H */
-- 
2.34.1

Re: FAILED: patch "[PATCH] KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t" failed to apply to 5.10-stable tree

[Marc Zyngier]

On Mon, 01 Jul 2024 11:56:57 +0100,
"Gowans, James" <jgowans@amazon.com> wrote:
> 
> 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.

Thanks for having a stab at this.

I eyeballed the two patches, and couldn't see anything untoward.
However, I haven't tested them, as life is too short to run
prehistoric kernels ;-).

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH 5.10.y] KVM: arm64: vgic-v4: Make the doorbell request robust w.r.t preemption

[Marc Zyngier]

On Mon, 01 Jul 2024 11:57:07 +0100,
James Gowans <jgowans@amazon.com> wrote:
> 
> From: Marc Zyngier <maz@kernel.org>
> 
> 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>
> 
> (cherry picked from commit b321c31c9b7b309dcde5e8854b741c8e6a9a05f0)
> 
> [modified to wrangle the vCPU flags directly instead of going through
> the flag helper macros as they have not yet been introduced. Also doing
> the flag wranging in the kvm_arch_vcpu_{un}blocking() hooks as the
> introduction of kvm_vcpu_wfi has not yet happened. See:
> 6109c5a6ab7f ("KVM: arm64: Move vGIC v4 handling for WFI out arch callback hook")]
> 
> Signed-off-by: James Gowans <jgowans@amazon.com>

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.