From: Ricardo Koller <ricarkol@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: James Clark <james.clark@arm.com>, Will Deacon <will@kernel.org>,
Marc Zyngier <maz@kernel.org>,
linux-kernel@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/1] KVM: arm64: PMU: Fix PMCR_EL0 reset value
Date: Tue, 13 Dec 2022 10:22:45 -0800 [thread overview]
Message-ID: <Y5jC9bAJ08xW1ZIA@google.com> (raw)
In-Reply-To: <Y5N3R+w3GF94hxHa@google.com>
On Fri, Dec 09, 2022 at 05:58:31PM +0000, Oliver Upton wrote:
> On Fri, Dec 09, 2022 at 04:44:46PM +0000, James Clark wrote:
> > ARMV8_PMU_PMCR_N_MASK is an unshifted value which results in the wrong
> > reset value for PMCR_EL0, so shift it to fix it.
>
> That's just mean. *_MASK tends to be a shifted mask, although it would
> appear that asm/perf_event.h does not follow this convention. Fixing
> that would be nice (as I'm sure somebody else will get burned by this),
> but for the sake of an immediate fix:
>
Even kvm-unit-tests does this:
arm/pmu.c:
#define PMU_PMCR_N_SHIFT 11
#define PMU_PMCR_N_MASK 0x1f
> > This fixes the following error when running qemu:
> >
> > $ qemu-system-aarch64 -cpu host -machine type=virt,accel=kvm -kernel ...
> >
> > target/arm/helper.c:1813: pmevcntr_rawwrite: Assertion `counter < pmu_num_counters(env)' failed.
> >
> > Fixes: 292e8f149476 ("KVM: arm64: PMU: Simplify PMCR_EL0 reset handling")
> > Signed-off-by: James Clark <james.clark@arm.com>
>
> Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
>
> --
> Thanks,
> Oliver
>
> > ---
> > arch/arm64/kvm/sys_regs.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> > index d5ee52d6bf73..c6cbfe6b854b 100644
> > --- a/arch/arm64/kvm/sys_regs.c
> > +++ b/arch/arm64/kvm/sys_regs.c
> > @@ -646,7 +646,7 @@ static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> > return;
> >
> > /* Only preserve PMCR_EL0.N, and reset the rest to 0 */
> > - pmcr = read_sysreg(pmcr_el0) & ARMV8_PMU_PMCR_N_MASK;
> > + pmcr = read_sysreg(pmcr_el0) & (ARMV8_PMU_PMCR_N_MASK << ARMV8_PMU_PMCR_N_SHIFT);
> > if (!kvm_supports_32bit_el0())
> > pmcr |= ARMV8_PMU_PMCR_LC;
> >
> > --
> > 2.25.1
> >
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-12-13 18:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-09 16:44 [PATCH 0/1] KVM: arm64: PMU: Fix PMCR_EL0 reset value James Clark
2022-12-09 16:44 ` [PATCH 1/1] " James Clark
2022-12-09 17:58 ` Oliver Upton
2022-12-10 11:16 ` Marc Zyngier
2022-12-12 6:08 ` Anshuman Khandual
2022-12-13 18:22 ` Ricardo Koller [this message]
2022-12-12 9:08 ` [PATCH 0/1] " Marc Zyngier
2023-01-03 17:57 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Y5jC9bAJ08xW1ZIA@google.com \
--to=ricarkol@google.com \
--cc=catalin.marinas@arm.com \
--cc=james.clark@arm.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=oliver.upton@linux.dev \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).