Hi Jorge,
On 05/30/2017 04:05 AM, Joerg Roedel wrote:
On Fri, May 19, 2017 at 11:12:29AM -0400, Brijesh Singh wrote:
From: Brijesh Singh <brijesh.singh@xxxxxxx>
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@xxxxxxx>
---
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?
nesting should not be an issue. all we're doing is avoiding the GVA->GPA
translation for the lowest level guest. The nested case should still use
the original code path and perform the nested page walk. I have verified
the nesting support and it all seem to work just fine. You can find the
original gpa_available patch here [1]
[1] https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?id=0f89b207b04a1a399e19d35293658e3a571da3d7
-Brijesh
