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Message-ID: <20160921171659.cvtkp5nf3r3afawi@pd.tnic>
Date: Wed, 21 Sep 2016 19:16:59 +0200
From: Borislav Petkov <bp@...e.de>
To: Brijesh Singh <brijesh.singh@....com>
Cc: simon.guinot@...uanux.org, linux-efi@...r.kernel.org,
kvm@...r.kernel.org, rkrcmar@...hat.com, matt@...eblueprint.co.uk,
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paul.gortmaker@...driver.com, hpa@...or.com,
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Subject: Re: [RFC PATCH v1 03/28] kvm: svm: Use the hardware provided GPA
instead of page walk
On Mon, Aug 22, 2016 at 07:24:07PM -0400, Brijesh Singh wrote:
> From: Tom Lendacky <thomas.lendacky@....com>
>
> When a guest causes a NPF which requires emulation, KVM sometimes walks
> the guest page tables to translate the GVA to a GPA. This is unnecessary
> most of the time on AMD hardware since the hardware provides the GPA in
> EXITINFO2.
>
> The only exception cases involve string operations involving rep or
> operations that use two memory locations. With rep, the GPA will only be
> the value of the initial NPF and with dual memory locations we won't know
> which memory address was translated into EXITINFO2.
>
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
> ---
> arch/x86/include/asm/kvm_emulate.h | 3 +++
> arch/x86/include/asm/kvm_host.h | 3 +++
> arch/x86/kvm/svm.c | 2 ++
> arch/x86/kvm/x86.c | 17 ++++++++++++++++-
> 4 files changed, 24 insertions(+), 1 deletion(-)
FWIW, LGTM. (Gotta love replying in acronyms :-))
Reviewed-by: Borislav Petkov <bp@...e.de>
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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