From: Joerg Roedel <joro@8bytes.org>
To: Brijesh Singh <brijesh.singh@amd.com>
Cc: pbonzini@redhat.com, rkrcmar@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
Thomas.Lendacky@amd.com
Subject: Re: [PATCH v2] KVM: x86: Avoid guest page table walk when gpa_available is set
Date: Tue, 30 May 2017 11:05:48 +0200 [thread overview]
Message-ID: <20170530090548.GA2764@8bytes.org> (raw)
In-Reply-To: <1495206749-25393-1-git-send-email-brijesh.singh@amd.com>
On Fri, May 19, 2017 at 11:12:29AM -0400, Brijesh Singh wrote:
> From: Brijesh Singh <brijesh.singh@amd.com>
>
> On AMD hardware when a guest causes a NPF which requires emulation,
> the vcpu->arch.gpa_available flag is set to indicate that cr2 contains
> a valid GPA.
>
> Currently, emulator_read_write_onepage() makes use of gpa_available flag
> to avoid a guest page walk for a known MMIO regions. Lets not limit
> the gpa_available optimization to just MMIO region. The patch extends
> the check to avoid page walk whenever gpa_available flag is set.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
> v1: http://marc.info/?l=kvm&m=149304930814202&w=2
>
> Changes in v2:
> - move gpa_val setting in pf_interception
>
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/svm.c | 4 ++++
> arch/x86/kvm/x86.c | 14 +++++++-------
> 3 files changed, 12 insertions(+), 7 deletions(-)
I havn't checked in detail, but maybe you have: Does that take nesting
into account, where we might run on a shadow nested page-table and we
actually get a nested gpa (which still needs translation) instead of a
normal gpa?
Joerg
next prev parent reply other threads:[~2017-05-30 9:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-19 15:12 [PATCH v2] KVM: x86: Avoid guest page table walk when gpa_available is set Brijesh Singh
2017-05-30 9:05 ` Joerg Roedel [this message]
2017-05-30 22:09 ` Brijesh Singh
2017-07-17 21:32 ` Brijesh Singh
2017-07-19 11:19 ` Radim Krčmář
2017-07-19 13:35 ` Brijesh Singh
2017-07-20 7:43 ` Radim Krčmář
2017-08-08 19:24 ` Brijesh Singh
2017-07-27 13:49 ` Paolo Bonzini
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