KVM: PPC: Book3S HV: Map single pages when doing dirty page logging
Subsystems (2)
PATCH 2/4 KVM: PPC: Book3S HV: Map single pages when doing dirty page logging
For radix guests, this makes KVM map guest memory as individual pages when dirty page logging is enabled for the memslot corresponding to the guest real address. Having a separate partition-scoped PTE for each system page mapped to the guest means that we have a separate dirty bit for each page, thus making the reported dirty bitmap more accurate. Without this, if part of guest memory is backed by transparent huge pages, the dirty status is reported at a 2MB granularity rather than a 64kB (or 4kB) granularity for that part, causing userspace to have to transmit more data when migrating the guest.
--- arch/powerpc/kvm/book3s_64_mmu_radix.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
arch/powerpc/kvm/book3s_64_mmu_radix.c +6 -2
@@ -683,6 +683,7 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,pte_t pte, *ptep;unsigned int shift, level;int ret; +bool large_enable;/* used to check for invalidations in progress */ mmu_seq = kvm->mmu_notifier_seq;
@@ -732,12 +733,15 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu, pte = *ptep;local_irq_enable (); +/* If we're logging dirty pages, always map single pages */ + large_enable = !(memslot->flags &KVM_MEM_LOG_DIRTY_PAGES ); +/* Get pte level from shift/size */ -if (shift =PUD_SHIFT && +if (large_enable && shift =PUD_SHIFT && (gpa & (PUD_SIZE -PAGE_SIZE )) = (hva & (PUD_SIZE -PAGE_SIZE ))) { level =2 ; - }else if (shift =PMD_SHIFT && + }else if (large_enable && shift =PMD_SHIFT && (gpa & (PMD_SIZE -PAGE_SIZE )) = (hva & (PMD_SIZE -PAGE_SIZE ))) { level =1 ;
Signature · 1 line
2.7.4
Quoted 11 lines · Paul Mackerras
For radix guests, this makes KVM map guest memory as individual pages when dirty page logging is enabled for the memslot corresponding to the
guest real address. Having a separate partition-scoped PTE for each system page mapped to the guest means that we have a separate dirty bit for each page, thus making the reported dirty bitmap more accurate.
Without this, if part of guest memory is backed by transparent huge pages, the dirty status is reported at a 2MB granularity rather than a 64kB (or 4kB) granularity for that part, causing userspace to have to transmit more data when migrating the guest.
Quoted 39 lines
Signed-off-by Paul Mackerras <[email protected]>--- arch/powerpc/kvm/book3s_64_mmu_radix.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)arch/powerpc/kvm/book3s_64_mmu_radix.c +1
-0@@ -683,6 +683,7 @@ int kvmppc_book3s_instantiate_page(structkvm_vcpu *vcpu, pte_t pte, *ptep;unsigned int shift, level;int ret; +bool large_enable;/* used to check for invalidations in progress */ arch/powerpc/kvm/book3s_64_mmu_radix.c +5
-2mmu_seq = kvm->mmu_notifier_seq;@@ -732,12 +733,15 @@ int kvmppc_book3s_instantiate_page(structkvm_vcpu *vcpu, pte = *ptep;local_irq_enable (); +/* If we're logging dirty pages, always map single pages */ + large_enable = !(memslot->flags &KVM_MEM_LOG_DIRTY_PAGES ); +/* Get pte level from shift/size */ -if (shift =PUD_SHIFT && +if (large_enable && shift =PUD_SHIFT && (gpa & (PUD_SIZE -PAGE_SIZE )) = (hva & (PUD_SIZE -PAGE_SIZE ))) { level =2 ; - }else if (shift =PMD_SHIFT && + }else if (large_enable && shift =PMD_SHIFT && (gpa & (PMD_SIZE -PAGE_SIZE )) = (hva & (PMD_SIZE -PAGE_SIZE ))) {level = 1;
Quoted 11 lines · Paul Mackerras
For radix guests, this makes KVM map guest memory as individual pages when dirty page logging is enabled for the memslot corresponding to the guest real address. Having a separate partition-scoped PTE for each system page mapped to the guest means that we have a separate dirty bit for each page, thus making the reported dirty bitmap more accurate. Without this, if part of guest memory is backed by transparent huge pages, the dirty status is reported at a 2MB granularity rather than a 64kB (or 4kB) granularity for that part, causing userspace to have to transmit more data when migrating the guest.
Signed-off-by Paul Mackerras <[email protected]>
Quoted 34 lines
--- arch/powerpc/kvm/book3s_64_mmu_radix.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)arch/powerpc/kvm/book3s_64_mmu_radix.c +6
-2@@ -683,6 +683,7 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,pte_t pte, *ptep;unsigned int shift, level;int ret; +bool large_enable;/* used to check for invalidations in progress */ mmu_seq = kvm->mmu_notifier_seq;@@ -732,12 +733,15 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu, pte = *ptep;local_irq_enable (); +/* If we're logging dirty pages, always map single pages */ + large_enable = !(memslot->flags &KVM_MEM_LOG_DIRTY_PAGES ); +/* Get pte level from shift/size */ -if (shift ==PUD_SHIFT && +if (large_enable && shift ==PUD_SHIFT && (gpa & (PUD_SIZE -PAGE_SIZE )) == (hva & (PUD_SIZE -PAGE_SIZE ))) { level =2 ; - }else if (shift ==PMD_SHIFT && + }else if (large_enable && shift ==PMD_SHIFT && (gpa & (PMD_SIZE -PAGE_SIZE )) == (hva & (PMD_SIZE -PAGE_SIZE ))) { level =1 ;
Signature · 4 lines
David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson