Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f460f679 authored by Paul Mackerras's avatar Paul Mackerras
Browse files

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: default avatarPaul Mackerras <paulus@ozlabs.org>
Reviewed-by: default avatarSuraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent f032b734

arch/powerpc/kvm/book3s_64_mmu_radix.c

+6 −2
Original line number Diff line number Diff line
@@ -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;