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Re: [Qemu-devel] [PATCH] i386/cpu/kvm: look at PMU's CPUID before settin
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From: |
Eduardo Habkost |
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Subject: |
Re: [Qemu-devel] [PATCH] i386/cpu/kvm: look at PMU's CPUID before setting MSRs |
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Date: |
Wed, 27 Dec 2017 15:39:51 -0200 |
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User-agent: |
Mutt/1.9.1 (2017-09-22) |
On Wed, Dec 27, 2017 at 05:04:26PM +0300, Jan Dakinevich wrote:
> Certain PMU-related MSRs are not supported for CPUs with PMU
> architecture below version 2. KVM rejects any access to them (see
> intel_is_valid_msr_idx routine in KVM), and QEMU fails on the following
> assertion:
>
> kvm_put_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed.
>
> QEMU also could fail if KVM exposes less fixed counters then 3. It could
> happen if host system run inside another hypervisor, which is tweaking
> PMU-related CPUID. To prevent possible fail, number of fixed counters now is
> obtained in the same way as number of GP counters.
>
> Reviewed-by: Roman Kagan <address@hidden>
> Signed-off-by: Jan Dakinevich <address@hidden>
Reviewed-by: Eduardo Habkost <address@hidden>
--
Eduardo