Re: [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages
On Wed, Sep 23, 2009 at 09:47:16PM +0300, Izik Eidus wrote: When using mmu notifiers, we are allowed to remove the page count reference tooken by get_user_pages to a specific page that is mapped inside the shadow page tables. This is needed so we can balance the pagecount against mapcount checking. (Right now kvm increase the pagecount and does not increase the mapcount when mapping page into shadow page table entry, so when comparing pagecount against mapcount, you have no reliable result.) Signed-off-by: Izik Eidus iei...@redhat.com Acked-by: Andrea Arcangeli aarca...@redhat.com -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages
When using mmu notifiers, we are allowed to remove the page count
reference tooken by get_user_pages to a specific page that is mapped
inside the shadow page tables.
This is needed so we can balance the pagecount against mapcount
checking.
(Right now kvm increase the pagecount and does not increase the
mapcount when mapping page into shadow page table entry,
so when comparing pagecount against mapcount, you have no
reliable result.)
Signed-off-by: Izik Eidus iei...@redhat.com
---
arch/x86/kvm/mmu.c |7 ++-
1 files changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index eca41ae..6c67b23 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -634,9 +634,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
if (*spte shadow_accessed_mask)
kvm_set_pfn_accessed(pfn);
if (is_writeble_pte(*spte))
- kvm_release_pfn_dirty(pfn);
- else
- kvm_release_pfn_clean(pfn);
+ kvm_set_pfn_dirty(pfn);
rmapp = gfn_to_rmap(kvm, sp-gfns[spte - sp-spt], sp-role.level);
if (!*rmapp) {
printk(KERN_ERR rmap_remove: %p %llx 0-BUG\n, spte, *spte);
@@ -1877,8 +1875,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64
*sptep,
page_header_update_slot(vcpu-kvm, sptep, gfn);
if (!was_rmapped) {
rmap_count = rmap_add(vcpu, sptep, gfn);
- if (!is_rmap_spte(*sptep))
- kvm_release_pfn_clean(pfn);
+ kvm_release_pfn_clean(pfn);
if (rmap_count RMAP_RECYCLE_THRESHOLD)
rmap_recycle(vcpu, sptep, gfn);
} else {
--
1.5.6.5
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[PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages
When using mmu notifiers, we are allowed to remove the page count
reference tooken by get_user_pages to a specific page that is mapped
inside the shadow page tables.
This is needed so we can balance the pagecount against mapcount
checking.
(Right now kvm increase the pagecount and does not increase the
mapcount when mapping page into shadow page table entry,
so when comparing pagecount against mapcount, you have no
reliable result.)
Signed-off-by: Izik Eidus iei...@redhat.com
---
arch/x86/kvm/mmu.c |7 ++-
1 files changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index eca41ae..6c67b23 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -634,9 +634,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
if (*spte shadow_accessed_mask)
kvm_set_pfn_accessed(pfn);
if (is_writeble_pte(*spte))
- kvm_release_pfn_dirty(pfn);
- else
- kvm_release_pfn_clean(pfn);
+ kvm_set_pfn_dirty(pfn);
rmapp = gfn_to_rmap(kvm, sp-gfns[spte - sp-spt], sp-role.level);
if (!*rmapp) {
printk(KERN_ERR rmap_remove: %p %llx 0-BUG\n, spte, *spte);
@@ -1877,8 +1875,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64
*sptep,
page_header_update_slot(vcpu-kvm, sptep, gfn);
if (!was_rmapped) {
rmap_count = rmap_add(vcpu, sptep, gfn);
- if (!is_rmap_spte(*sptep))
- kvm_release_pfn_clean(pfn);
+ kvm_release_pfn_clean(pfn);
if (rmap_count RMAP_RECYCLE_THRESHOLD)
rmap_recycle(vcpu, sptep, gfn);
} else {
--
1.5.6.5
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Re: [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages.
Izik Eidus wrote: Marcelo Tosatti wrote: On Tue, Mar 31, 2009 at 03:00:02AM +0300, Izik Eidus wrote: When using mmu notifiers, we are allowed to remove the page count reference tooken by get_user_pages to a specific page that is mapped inside the shadow page tables. This is needed so we can balance the pagecount against mapcount checking. (Right now kvm increase the pagecount and does not increase the mapcount when mapping page into shadow page table entry, so when comparing pagecount against mapcount, you have no reliable result.) IMO ifdef'ing CONFIG_MMU_NOTIFIERS here (and keeping the ref if unset) instead of in the backward compat code gives less room for headaches. That was the first version of this patch, Avi preferred not to do it... Avi, You mind if i changed it to use the IFDEF ? -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages.
Izik Eidus wrote: Izik Eidus wrote: Marcelo Tosatti wrote: On Tue, Mar 31, 2009 at 03:00:02AM +0300, Izik Eidus wrote: When using mmu notifiers, we are allowed to remove the page count reference tooken by get_user_pages to a specific page that is mapped inside the shadow page tables. This is needed so we can balance the pagecount against mapcount checking. (Right now kvm increase the pagecount and does not increase the mapcount when mapping page into shadow page table entry, so when comparing pagecount against mapcount, you have no reliable result.) IMO ifdef'ing CONFIG_MMU_NOTIFIERS here (and keeping the ref if unset) instead of in the backward compat code gives less room for headaches. That was the first version of this patch, Avi preferred not to do it... Avi, You mind if i changed it to use the IFDEF ? No, let's not have too many ifdefs in the code. I'll hack it in hack-module.awk. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages.
On Tue, Mar 31, 2009 at 03:00:02AM +0300, Izik Eidus wrote: When using mmu notifiers, we are allowed to remove the page count reference tooken by get_user_pages to a specific page that is mapped inside the shadow page tables. This is needed so we can balance the pagecount against mapcount checking. (Right now kvm increase the pagecount and does not increase the mapcount when mapping page into shadow page table entry, so when comparing pagecount against mapcount, you have no reliable result.) IMO ifdef'ing CONFIG_MMU_NOTIFIERS here (and keeping the ref if unset) instead of in the backward compat code gives less room for headaches. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages.
Marcelo Tosatti wrote: On Tue, Mar 31, 2009 at 03:00:02AM +0300, Izik Eidus wrote: When using mmu notifiers, we are allowed to remove the page count reference tooken by get_user_pages to a specific page that is mapped inside the shadow page tables. This is needed so we can balance the pagecount against mapcount checking. (Right now kvm increase the pagecount and does not increase the mapcount when mapping page into shadow page table entry, so when comparing pagecount against mapcount, you have no reliable result.) IMO ifdef'ing CONFIG_MMU_NOTIFIERS here (and keeping the ref if unset) instead of in the backward compat code gives less room for headaches. That was the first version of this patch, Avi preferred not to do it... -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH 1/3] kvm: dont hold pagecount reference for mapped sptes pages.
When using mmu notifiers, we are allowed to remove the page count
reference tooken by get_user_pages to a specific page that is mapped
inside the shadow page tables.
This is needed so we can balance the pagecount against mapcount
checking.
(Right now kvm increase the pagecount and does not increase the
mapcount when mapping page into shadow page table entry,
so when comparing pagecount against mapcount, you have no
reliable result.)
Signed-off-by: Izik Eidus iei...@redhat.com
---
arch/x86/kvm/mmu.c |7 ++-
1 files changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b625ed4..df8fbaf 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -567,9 +567,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
if (*spte shadow_accessed_mask)
kvm_set_pfn_accessed(pfn);
if (is_writeble_pte(*spte))
- kvm_release_pfn_dirty(pfn);
- else
- kvm_release_pfn_clean(pfn);
+ kvm_set_pfn_dirty(pfn);
rmapp = gfn_to_rmap(kvm, sp-gfns[spte - sp-spt], is_large_pte(*spte));
if (!*rmapp) {
printk(KERN_ERR rmap_remove: %p %llx 0-BUG\n, spte, *spte);
@@ -1812,8 +1810,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64
*shadow_pte,
page_header_update_slot(vcpu-kvm, shadow_pte, gfn);
if (!was_rmapped) {
rmap_add(vcpu, shadow_pte, gfn, largepage);
- if (!is_rmap_pte(*shadow_pte))
- kvm_release_pfn_clean(pfn);
+ kvm_release_pfn_clean(pfn);
} else {
if (was_writeble)
kvm_release_pfn_dirty(pfn);
--
1.5.6.5
--
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