Re: [PATCH 3/4] KVM: MMU: notrap it if gpte's reserved is set

From: Avi Kivity
Date: Sun Nov 14 2010 - 05:56:21 EST


On 11/12/2010 12:34 PM, Xiao Guangrong wrote:
We can past the page fault to guest directly if gpte's reserved
is set


How can that work? shadow_notrap_nonpresent_pte causes a fault with PFEC.P=PFEC.RSVD=0, while we need PFEC.P=PFEC.RSVD=1.

Signed-off-by: Xiao Guangrong<xiaoguangrong@xxxxxxxxxxxxxx>
---
arch/x86/kvm/paging_tmpl.h | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 291342d..952357a 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -760,6 +760,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
pt_element_t gpte;
gpa_t pte_gpa;
gfn_t gfn;
+ bool gpte_invalid;

if (!is_shadow_present_pte(sp->spt[i]))
continue;
@@ -771,12 +772,13 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
return -EINVAL;

gfn = gpte_to_gfn(gpte);
- if (is_rsvd_bits_set(&vcpu->arch.mmu, gpte, PT_PAGE_TABLE_LEVEL)
- || gfn != sp->gfns[i] || !is_present_gpte(gpte)
- || !(gpte& PT_ACCESSED_MASK)) {
+ gpte_invalid = is_present_gpte(gpte) ||
+ is_rsvd_bits_set(&vcpu->arch.mmu, gpte, PT_PAGE_TABLE_LEVEL);

Shouldn't that be &&?

+ if (gpte_invalid || gfn != sp->gfns[i] ||
+ !(gpte& PT_ACCESSED_MASK)) {
u64 nonpresent;

- if (is_present_gpte(gpte) || !clear_unsync)
+ if (gpte_invalid || !clear_unsync)
nonpresent = shadow_trap_nonpresent_pte;
else
nonpresent = shadow_notrap_nonpresent_pte;


--
error compiling committee.c: too many arguments to function

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