From: Marc Zyngier <maz@kernel.org>
To: Andrew Murray <andrew.murray@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v4 2/3] KVM: arm64: limit PMU version to ARMv8.4
Date: Thu, 23 Jan 2020 17:04:36 +0000 [thread overview]
Message-ID: <e59eeba41a2721e4cedb7172e714141c@kernel.org> (raw)
In-Reply-To: <20200123115852.55595-3-andrew.murray@arm.com>
On 2020-01-23 11:58, Andrew Murray wrote:
> ARMv8.5-PMU introduces 64-bit event counters, however KVM doesn't yet
> support this. Let's trap the Debug Feature Registers in order to limit
> PMUVer/PerfMon in the Debug Feature Registers to PMUv3 for ARMv8.4.
>
> Signed-off-by: Andrew Murray <andrew.murray@arm.com>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
> arch/arm64/include/asm/sysreg.h | 5 +++++
> arch/arm64/kvm/sys_regs.c | 11 +++++++++++
> 2 files changed, 16 insertions(+)
>
> diff --git a/arch/arm64/include/asm/sysreg.h
> b/arch/arm64/include/asm/sysreg.h
> index 6e919fafb43d..d969df417f88 100644
> --- a/arch/arm64/include/asm/sysreg.h
> +++ b/arch/arm64/include/asm/sysreg.h
> @@ -672,6 +672,11 @@
> #define ID_AA64DFR0_TRACEVER_SHIFT 4
> #define ID_AA64DFR0_DEBUGVER_SHIFT 0
>
> +#define ID_DFR0_PERFMON_SHIFT 24
> +
> +#define ID_DFR0_EL1_PMUVER_8_4 5
> +#define ID_AA64DFR0_EL1_PMUVER_8_4 5
> +
> #define ID_ISAR5_RDM_SHIFT 24
> #define ID_ISAR5_CRC32_SHIFT 16
> #define ID_ISAR5_SHA2_SHIFT 12
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 9f2165937f7d..028c93a88a51 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1085,6 +1085,17 @@ static u64 read_id_reg(const struct kvm_vcpu
> *vcpu,
> (0xfUL << ID_AA64ISAR1_API_SHIFT) |
> (0xfUL << ID_AA64ISAR1_GPA_SHIFT) |
> (0xfUL << ID_AA64ISAR1_GPI_SHIFT));
> + } else if (id == SYS_ID_AA64DFR0_EL1) {
> + /* Limit guests to PMUv3 for ARMv8.4 */
> + val = cpuid_feature_cap_signed_field_width(val,
> + ID_AA64DFR0_PMUVER_SHIFT,
> + 4, ID_AA64DFR0_EL1_PMUVER_8_4);
> + } else if (id == SYS_ID_DFR0_EL1) {
> + /* Limit guests to PMUv3 for ARMv8.4 */
> + val = cpuid_feature_cap_signed_field_width(val,
> + ID_DFR0_PERFMON_SHIFT,
> + 4, ID_DFR0_EL1_PMUVER_8_4);
I dont think this is right. Even today, we don't have support for PMMIR,
so pretending we support v8.4 is not true (the guest will get an UNDEF).
I would really stick to ARMv8.1 support here.
You could post it as a fix, to be taken right away.
M.
--
Jazz is not dead. It just smells funny...
_______________________________________________
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:[~2020-01-23 17:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 11:58 [PATCH v4 0/3] arm64: perf: Add support for ARMv8.5-PMU 64-bit counters Andrew Murray
2020-01-23 11:58 ` [PATCH v4 1/3] arm64: cpufeature: Extract capped fields Andrew Murray
2020-01-23 11:58 ` [PATCH v4 2/3] KVM: arm64: limit PMU version to ARMv8.4 Andrew Murray
2020-01-23 17:04 ` Marc Zyngier [this message]
2020-01-23 11:58 ` [PATCH v4 3/3] arm64: perf: Add support for ARMv8.5-PMU 64-bit counters Andrew Murray
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=e59eeba41a2721e4cedb7172e714141c@kernel.org \
--to=maz@kernel.org \
--cc=andrew.murray@arm.com \
--cc=catalin.marinas@arm.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=suzuki.poulose@arm.com \
--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).