KVM: MMU: handle large host sptes on invlpg/resync

KVM: MMU: handle large host sptes on invlpg/resync

[Marcelo Tosatti]

The invlpg and sync walkers lack knowledge of large host sptes,
descending to non-existant pagetable level.

Stop at directory level in such case.

Fixes SMP Windows XP with hugepages.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 9871d9d..3b86df6 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1006,7 +1006,7 @@ static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
 	for_each_unsync_children(sp->unsync_child_bitmap, i) {
 		u64 ent = sp->spt[i];
 
-		if (is_shadow_present_pte(ent)) {
+		if (is_shadow_present_pte(ent) && !is_large_pte(ent)) {
 			struct kvm_mmu_page *child;
 			child = page_header(ent & PT64_BASE_ADDR_MASK);
 
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index d206401..9fd78b6 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -472,14 +472,19 @@ static int FNAME(shadow_invlpg_entry)(struct kvm_shadow_walk *_sw,
 	struct shadow_walker *sw =
 		container_of(_sw, struct shadow_walker, walker);
 
-	if (level == PT_PAGE_TABLE_LEVEL) {
+	/* FIXME: properly handle invlpg on large guest pages */
+	if (level == PT_PAGE_TABLE_LEVEL ||
+	    ((level == PT_DIRECTORY_LEVEL) && is_large_pte(*sptep))) {
 		struct kvm_mmu_page *sp = page_header(__pa(sptep));
 
 		sw->pte_gpa = (sp->gfn << PAGE_SHIFT);
 		sw->pte_gpa += (sptep - sp->spt) * sizeof(pt_element_t);
 
-		if (is_shadow_present_pte(*sptep))
+		if (is_shadow_present_pte(*sptep)) {
 			rmap_remove(vcpu->kvm, sptep);
+			if (is_large_pte(*sptep))
+				--vcpu->kvm->stat.lpages;
+		}
 		set_shadow_pte(sptep, shadow_trap_nonpresent_pte);
 		return 1;
 	}

Re: KVM: MMU: handle large host sptes on invlpg/resync

[Bernhard Held]

> The invlpg and sync walkers lack knowledge of large host sptes,
> descending to non-existant pagetable level.
> 
> Stop at directory level in such case.
> 
> Fixes SMP Windows XP with hugepages.
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
I happily confirm that with Marcelo's patch applied on kvm-81 my WXP
guest is working again with hugepages and SMP.

Thanks for the quick fix!

Bernhard

Re: KVM: MMU: handle large host sptes on invlpg/resync

[Avi Kivity]

Marcelo Tosatti wrote:
> The invlpg and sync walkers lack knowledge of large host sptes,
> descending to non-existant pagetable level.
>
> Stop at directory level in such case.
>
> Fixes SMP Windows XP with hugepages.
>
>   

Applied, thanks.

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