linux-kernel - Re: [kvm-unit-tests PATCH] x86: pmu: Test full-width counter writes support

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Message-ID: <b1a5472b-f7d0-82b0-e753-dabf81254488@redhat.com>
Date:   Tue, 16 Jun 2020 12:49:17 +0200
From:   Thomas Huth <thuth@...hat.com>
To:     Like Xu <like.xu@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [kvm-unit-tests PATCH] x86: pmu: Test full-width counter writes
 support

On 29/05/2020 09.43, Like Xu wrote:
> When the full-width writes capability is set, use the alternative MSR
> range to write larger sign counter values (up to GP counter width).
> 
> Signed-off-by: Like Xu <like.xu@...ux.intel.com>
> ---
>  lib/x86/msr.h |   1 +
>  x86/pmu.c     | 125 ++++++++++++++++++++++++++++++++++++++++----------
>  2 files changed, 102 insertions(+), 24 deletions(-)
[...]
> @@ -452,6 +468,66 @@ static void check_running_counter_wrmsr(void)
>  	report_prefix_pop();
>  }
>  
> +static void check_counters(void)
> +{
> +	check_gp_counters();
> +	check_fixed_counters();
> +	check_rdpmc();
> +	check_counters_many();
> +	check_counter_overflow();
> +	check_gp_counter_cmask();
> +	check_running_counter_wrmsr();
> +}
> +
> +static void do_unsupported_width_counter_write(void *index)
> +{
> +	wrmsr(MSR_IA32_PMC0 + *((int *) index), 0xffffff0123456789ull);
> +}
> +
> +static void  check_gp_counters_write_width(void)
> +{
> +	u64 val_64 = 0xffffff0123456789ull;
> +	u64 val_32 = val_64 & ((1ul << 32) - 1);
 Hi,

this broke compilation on 32-bit hosts:

 https://travis-ci.com/github/huth/kvm-unit-tests/jobs/349654654#L710

Fix should be easy, I guess - either use 1ull or specify the mask
0xffffffff directly.

 Thomas