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Date:   Tue, 13 Dec 2022 10:46:18 +0100
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Subject: Re: [PATCH 03/14] KVM: selftests: Fix divide-by-zero bug in
 memslot_perf_test
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To:     Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Marc Zyngier <maz@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>
Cc:     James Morse <james.morse@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Oliver Upton <oliver.upton@linux.dev>,
        Tom Rix <trix@redhat.com>, kvm@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        kvmarm@lists.cs.columbia.edu, linux-riscv@lists.infradead.org,
        llvm@lists.linux.dev, linux-kernel@vger.kernel.org,
        Ricardo Koller <ricarkol@google.com>,
        Aaron Lewis <aaronlewis@google.com>,
        Raghavendra Rao Ananta <rananta@google.com>
References: <20221213001653.3852042-1-seanjc@google.com>
 <20221213001653.3852042-4-seanjc@google.com>
From:   =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= <philmd@linaro.org>
In-Reply-To: <20221213001653.3852042-4-seanjc@google.com>
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On 13/12/22 01:16, Sean Christopherson wrote:
> Check that the number of pages per slot is non-zero in get_max_slots()
> prior to computing the remaining number of pages.  clang generates code
> that uses an actual DIV for calculating the remaining, which causes a #DE
> if the total number of pages is less than the number of slots.
> 
>    traps: memslot_perf_te[97611] trap divide error ip:4030c4 sp:7ffd18ae58f0
>           error:0 in memslot_perf_test[401000+cb000]
> 
> Fixes: a69170c65acd ("KVM: selftests: memslot_perf_test: Report optimal memory slots")
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
>   tools/testing/selftests/kvm/memslot_perf_test.c | 3 +++
>   1 file changed, 3 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>