lkml.org 
[lkml]   [2016]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4/4] KVM: MMU: skip obsolete sp in for_each_gfn_*()
Date
The obsolete sp should not be used on current vCPUs and should not hurt
vCPU's running, so skip it from for_each_gfn_sp() and
for_each_gfn_indirect_valid_sp()

The side effort is we will double check role.invalid in kvm_mmu_get_page()
but i think it is okay as role is well cached

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
arch/x86/kvm/mmu.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index c396e8b..4d66a9e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1906,18 +1906,17 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
* since it has been deleted from active_mmu_pages but still can be found
* at hast list.
*
- * for_each_gfn_indirect_valid_sp has skipped that kind of page and
- * kvm_mmu_get_page(), the only user of for_each_gfn_sp(), has skipped
- * all the obsolete pages.
+ * for_each_gfn_valid_sp() has skipped that kind of pages.
*/
-#define for_each_gfn_sp(_kvm, _sp, _gfn) \
+#define for_each_gfn_valid_sp(_kvm, _sp, _gfn) \
hlist_for_each_entry(_sp, \
&(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
- if ((_sp)->gfn != (_gfn)) {} else
+ if ((_sp)->gfn != (_gfn) || is_obsolete_sp((_kvm), (_sp)) \
+ || (_sp)->role.invalid) {} else

#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \
- for_each_gfn_sp(_kvm, _sp, _gfn) \
- if ((_sp)->role.direct || (_sp)->role.invalid) {} else
+ for_each_gfn_valid_sp(_kvm, _sp, _gfn) \
+ if ((_sp)->role.direct) {} else

/* @sp->gfn should be write-protected at the call site */
static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
@@ -1958,6 +1957,11 @@ static void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { }
static void mmu_audit_disable(void) { }
#endif

+static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+ return unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen);
+}
+
static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
struct list_head *invalid_list)
{
@@ -2092,11 +2096,6 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sp);
}

-static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
-{
- return unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen);
-}
-
static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
gfn_t gfn,
gva_t gaddr,
@@ -2123,10 +2122,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
role.quadrant = quadrant;
}
- for_each_gfn_sp(vcpu->kvm, sp, gfn) {
- if (is_obsolete_sp(vcpu->kvm, sp))
- continue;
-
+ for_each_gfn_valid_sp(vcpu->kvm, sp, gfn) {
if (!need_sync && sp->unsync)
need_sync = true;

--
1.8.3.1
\
 
 \ /
  Last update: 2016-03-25 15:21    [W:0.059 / U:0.436 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site