From f460f6791a0224cfb019462363caa014c3aec8d7 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Wed, 12 Dec 2018 15:16:17 +1100 Subject: [PATCH] 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. Signed-off-by: Paul Mackerras Reviewed-by: Suraj Jitindar Singh Reviewed-by: David Gibson Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_64_mmu_radix.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index d68162ee159b..87ad35e0b138 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -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; -- 2.30.2