linux-kernel - Re: [PATCH v2 1/5] KVM: selftests: Remove address rounding in guest code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20201104105450.t2frosra4mvixrwi@kamzik.brq.redhat.com>
Date:   Wed, 4 Nov 2020 11:54:50 +0100
From:   Andrew Jones <drjones@...hat.com>
To:     Ben Gardon <bgardon@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.com>, Peter Shier <pshier@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Thomas Huth <thuth@...hat.com>,
        Peter Feiner <pfeiner@...gle.com>
Subject: Re: [PATCH v2 1/5] KVM: selftests: Remove address rounding in guest
 code

On Tue, Nov 03, 2020 at 03:49:48PM -0800, Ben Gardon wrote:
> Rounding the address the guest writes to a host page boundary
> will only have an effect if the host page size is larger than the guest
> page size, but in that case the guest write would still go to the same
> host page. There's no reason to round the address down, so remove the
> rounding to simplify the demand paging test.
> 
> Signed-off-by: Ben Gardon <bgardon@...gle.com>
> ---
>  tools/testing/selftests/kvm/demand_paging_test.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index 360cd3ea4cd67..32a42eafc6b5c 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -103,7 +103,6 @@ static void guest_code(uint32_t vcpu_id)
>  	for (i = 0; i < pages; i++) {
>  		uint64_t addr = gva + (i * guest_page_size);
>  
> -		addr &= ~(host_page_size - 1);
>  		*(uint64_t *)addr = 0x0123456789ABCDEF;
>  	}
>  
> -- 
> 2.29.1.341.ge80a0c044ae-goog
>

Reviewed-by: Andrew Jones <drjones@...hat.com>