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

[Greg KH <gregkh@linuxfoundation.org>]

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