[PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Raghavendra Rao Ananta]

commit 54bbee190d42166209185d89070c58a343bf514b upstream.

DDI0487K.a D13.3.1 describes the PMU overflow condition, which evaluates
to true if any counter's global enable (PMCR_EL0.E), overflow flag
(PMOVSSET_EL0[n]), and interrupt enable (PMINTENSET_EL1[n]) are all 1.
Of note, this does not require a counter to be enabled
(i.e. PMCNTENSET_EL0[n] = 1) to generate an overflow.

Align kvm_pmu_overflow_status() with the reality of the architecture
and stop using PMCNTENSET_EL0 as part of the overflow condition. The
bug was discovered while running an SBSA PMU test [*], which only sets
PMCR.E, PMOVSSET<0>, PMINTENSET<0>, and expects an overflow interrupt.

Cc: stable@vger.kernel.org
Fixes: 76d883c4e640 ("arm64: KVM: Add access handler for PMOVSSET and PMOVSCLR register")
Link: https://github.com/ARM-software/sbsa-acs/blob/master/test_pool/pmu/operating_system/test_pmu001.c
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
[ oliver: massaged changelog ]
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241120005230.2335682-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 virt/kvm/arm/pmu.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 6d52fd50c1ff..b92b1d406374 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -195,7 +195,6 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
 
 	if ((__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E)) {
 		reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
-		reg &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
 		reg &= __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
 		reg &= kvm_pmu_valid_counter_mask(vcpu);
 	}
-- 
2.47.0.338.g60cca15819-goog

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 54bbee190d42166209185d89070c58a343bf514b


Status in newer kernel trees:
6.12.y | Present (different SHA1: 2a68705a5469)

Note: The patch differs from the upstream commit:
---
Failed to apply patch cleanly, falling back to interdiff...
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y       |  Failed     |  N/A       |
| stable/linux-6.11.y       |  Failed     |  N/A       |
| stable/linux-6.6.y        |  Failed     |  N/A       |
| stable/linux-6.1.y        |  Failed     |  N/A       |
| stable/linux-5.15.y       |  Failed     |  N/A       |
| stable/linux-5.10.y       |  Failed     |  N/A       |
| stable/linux-5.4.y        |  Success    |  Success   |
| stable/linux-4.19.y       |  Success    |  Success   |

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Greg KH]

On Tue, Dec 03, 2024 at 07:02:36PM +0000, Raghavendra Rao Ananta wrote:
> commit 54bbee190d42166209185d89070c58a343bf514b upstream.
> 
> DDI0487K.a D13.3.1 describes the PMU overflow condition, which evaluates
> to true if any counter's global enable (PMCR_EL0.E), overflow flag
> (PMOVSSET_EL0[n]), and interrupt enable (PMINTENSET_EL1[n]) are all 1.
> Of note, this does not require a counter to be enabled
> (i.e. PMCNTENSET_EL0[n] = 1) to generate an overflow.
> 
> Align kvm_pmu_overflow_status() with the reality of the architecture
> and stop using PMCNTENSET_EL0 as part of the overflow condition. The
> bug was discovered while running an SBSA PMU test [*], which only sets
> PMCR.E, PMOVSSET<0>, PMINTENSET<0>, and expects an overflow interrupt.
> 
> Cc: stable@vger.kernel.org
> Fixes: 76d883c4e640 ("arm64: KVM: Add access handler for PMOVSSET and PMOVSCLR register")
> Link: https://github.com/ARM-software/sbsa-acs/blob/master/test_pool/pmu/operating_system/test_pmu001.c
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> [ oliver: massaged changelog ]
> Reviewed-by: Marc Zyngier <maz@kernel.org>
> Link: https://lore.kernel.org/r/20241120005230.2335682-2-oliver.upton@linux.dev
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> ---
>  virt/kvm/arm/pmu.c | 1 -
>  1 file changed, 1 deletion(-)

What branch is this patch for?

thanks,

greg k-h

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Greg KH]

On Tue, Dec 03, 2024 at 07:02:36PM +0000, Raghavendra Rao Ananta wrote:
> commit 54bbee190d42166209185d89070c58a343bf514b upstream.
> 
> DDI0487K.a D13.3.1 describes the PMU overflow condition, which evaluates
> to true if any counter's global enable (PMCR_EL0.E), overflow flag
> (PMOVSSET_EL0[n]), and interrupt enable (PMINTENSET_EL1[n]) are all 1.
> Of note, this does not require a counter to be enabled
> (i.e. PMCNTENSET_EL0[n] = 1) to generate an overflow.
> 
> Align kvm_pmu_overflow_status() with the reality of the architecture
> and stop using PMCNTENSET_EL0 as part of the overflow condition. The
> bug was discovered while running an SBSA PMU test [*], which only sets
> PMCR.E, PMOVSSET<0>, PMINTENSET<0>, and expects an overflow interrupt.
> 
> Cc: stable@vger.kernel.org
> Fixes: 76d883c4e640 ("arm64: KVM: Add access handler for PMOVSSET and PMOVSCLR register")
> Link: https://github.com/ARM-software/sbsa-acs/blob/master/test_pool/pmu/operating_system/test_pmu001.c
> Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> [ oliver: massaged changelog ]
> Reviewed-by: Marc Zyngier <maz@kernel.org>
> Link: https://lore.kernel.org/r/20241120005230.2335682-2-oliver.upton@linux.dev
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> ---
>  virt/kvm/arm/pmu.c | 1 -
>  1 file changed, 1 deletion(-)

What kernel branch(es) is this backport for?

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Raghavendra Rao Ananta]

Hi Greg,

This is an adjustment of the original upstream patch aimed towards the
4.19.y stable branch.

Thank you.
Raghavendra

On Thu, Dec 12, 2024 at 12:27 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Tue, Dec 03, 2024 at 07:02:36PM +0000, Raghavendra Rao Ananta wrote:
> > commit 54bbee190d42166209185d89070c58a343bf514b upstream.
> >
> > DDI0487K.a D13.3.1 describes the PMU overflow condition, which evaluates
> > to true if any counter's global enable (PMCR_EL0.E), overflow flag
> > (PMOVSSET_EL0[n]), and interrupt enable (PMINTENSET_EL1[n]) are all 1.
> > Of note, this does not require a counter to be enabled
> > (i.e. PMCNTENSET_EL0[n] = 1) to generate an overflow.
> >
> > Align kvm_pmu_overflow_status() with the reality of the architecture
> > and stop using PMCNTENSET_EL0 as part of the overflow condition. The
> > bug was discovered while running an SBSA PMU test [*], which only sets
> > PMCR.E, PMOVSSET<0>, PMINTENSET<0>, and expects an overflow interrupt.
> >
> > Cc: stable@vger.kernel.org
> > Fixes: 76d883c4e640 ("arm64: KVM: Add access handler for PMOVSSET and PMOVSCLR register")
> > Link: https://github.com/ARM-software/sbsa-acs/blob/master/test_pool/pmu/operating_system/test_pmu001.c
> > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> > [ oliver: massaged changelog ]
> > Reviewed-by: Marc Zyngier <maz@kernel.org>
> > Link: https://lore.kernel.org/r/20241120005230.2335682-2-oliver.upton@linux.dev
> > Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> > ---
> >  virt/kvm/arm/pmu.c | 1 -
> >  1 file changed, 1 deletion(-)
>
> What kernel branch(es) is this backport for?

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Greg KH]

On Thu, Dec 12, 2024 at 09:41:28AM -0800, Raghavendra Rao Ananta wrote:
> Hi Greg,
> 
> This is an adjustment of the original upstream patch aimed towards the
> 4.19.y stable branch.

4.19.y is end-of-life, so there's nothing we can do there.  But what
about 5.4.y?  If it matters there, please resend it in a format we can
apply it in for that tree.

thanks,

greg k-h

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Raghavendra Rao Ananta]

On Thu, Dec 12, 2024 at 10:07 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Thu, Dec 12, 2024 at 09:41:28AM -0800, Raghavendra Rao Ananta wrote:
> > Hi Greg,
> >
> > This is an adjustment of the original upstream patch aimed towards the
> > 4.19.y stable branch.
>
> 4.19.y is end-of-life, so there's nothing we can do there.  But what
> about 5.4.y?  If it matters there, please resend it in a format we can
> apply it in for that tree.

The version of the patch from this thread applies to 5.4.y as well. Do
you want me to resend it or will you be able to pick this up?

Thank you.
Raghavendra

Raghavendra

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Greg KH]

On Thu, Dec 12, 2024 at 10:52:07AM -0800, Raghavendra Rao Ananta wrote:
> On Thu, Dec 12, 2024 at 10:07 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Thu, Dec 12, 2024 at 09:41:28AM -0800, Raghavendra Rao Ananta wrote:
> > > Hi Greg,
> > >
> > > This is an adjustment of the original upstream patch aimed towards the
> > > 4.19.y stable branch.
> >
> > 4.19.y is end-of-life, so there's nothing we can do there.  But what
> > about 5.4.y?  If it matters there, please resend it in a format we can
> > apply it in for that tree.
> 
> The version of the patch from this thread applies to 5.4.y as well. Do
> you want me to resend it or will you be able to pick this up?

Please resend it.

thanks,

greg k-h

[PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Raghavendra Rao Ananta]

commit 54bbee190d42166209185d89070c58a343bf514b upstream.

DDI0487K.a D13.3.1 describes the PMU overflow condition, which evaluates
to true if any counter's global enable (PMCR_EL0.E), overflow flag
(PMOVSSET_EL0[n]), and interrupt enable (PMINTENSET_EL1[n]) are all 1.
Of note, this does not require a counter to be enabled
(i.e. PMCNTENSET_EL0[n] = 1) to generate an overflow.

Align kvm_pmu_overflow_status() with the reality of the architecture
and stop using PMCNTENSET_EL0 as part of the overflow condition. The
bug was discovered while running an SBSA PMU test [*], which only sets
PMCR.E, PMOVSSET<0>, PMINTENSET<0>, and expects an overflow interrupt.

Cc: stable@vger.kernel.org
Fixes: 76d883c4e640 ("arm64: KVM: Add access handler for PMOVSSET and PMOVSCLR register")
Link: https://github.com/ARM-software/sbsa-acs/blob/master/test_pool/pmu/operating_system/test_pmu001.c
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
[ oliver: massaged changelog ]
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241120005230.2335682-2-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 virt/kvm/arm/pmu.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 4c08fd009768..9732c5e0ed22 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -357,7 +357,6 @@ static u64 kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
 
 	if ((__vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMU_PMCR_E)) {
 		reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
-		reg &= __vcpu_sys_reg(vcpu, PMCNTENSET_EL0);
 		reg &= __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
 		reg &= kvm_pmu_valid_counter_mask(vcpu);
 	}

base-commit: 6708005a36cfdb32aa991ebd9ea172e1183231ef
-- 
2.47.1.613.gc27f4b7a9f-goog

Re: [PATCH] KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: 54bbee190d42166209185d89070c58a343bf514b


Status in newer kernel trees:
6.12.y | Present (different SHA1: 8b6916f4cf7d)

Note: The patch differs from the upstream commit:
---
Failed to apply patch cleanly, falling back to interdiff...

interdiff error output:
/home/sasha/stable/mailbot.sh: line 525: interdiff: command not found
interdiff failed, falling back to standard diff...
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y       |  Failed     |  N/A       |
| stable/linux-6.6.y        |  Failed     |  N/A       |
| stable/linux-6.1.y        |  Failed     |  N/A       |
| stable/linux-5.15.y       |  Failed     |  N/A       |
| stable/linux-5.10.y       |  Failed     |  N/A       |
| stable/linux-5.4.y        |  Success    |  Success   |