This adds code to flush the partition-scoped page tables for a radix
guest when dirty tracking is turned on or off for a memslot. Only the
guest real addresses covered by the memslot are flushed. The reason
for this is to get rid of any 2M PTEs in the partition-scoped page
tables that correspond to host transparent huge pages, so that page
dirtiness is tracked at a system page (4k or 64k) granularity rather
than a 2M granularity. The page tables are also flushed when turning
dirty tracking off so that the memslot's address space can be
repopulated with THPs if possible.
To do this, we add a new function kvmppc_radix_flush_memslot(). Since
this does what's needed for kvmppc_core_flush_memslot_hv() on a radix
guest, we now make kvmppc_core_flush_memslot_hv() call the new
kvmppc_radix_flush_memslot() rather than calling kvm_unmap_radix()
for each page in the memslot. This has the effect of fixing a bug in
that kvmppc_core_flush_memslot_hv() was previously calling
kvm_unmap_radix() without holding the kvm->mmu_lock spinlock, which
is required to be held.
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
---
arch/powerpc/include/asm/kvm_book3s.h | 2 ++
arch/powerpc/kvm/book3s_64_mmu_hv.c | 9 +++++----
arch/powerpc/kvm/book3s_64_mmu_radix.c | 20 ++++++++++++++++++++
arch/powerpc/kvm/book3s_hv.c | 17 +++++++++++++++++
4 files changed, 44 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index 728d2b7..f8a5ac8 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -222,6 +222,8 @@ extern int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
unsigned long gfn);
extern long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm,
struct kvm_memory_slot *memslot, unsigned long *map);
+extern void kvmppc_radix_flush_memslot(struct kvm *kvm,
+ const struct kvm_memory_slot *memslot);
extern int kvmhv_get_rmmu_info(struct kvm *kvm, struct kvm_ppc_rmmu_info *info);
/* XXX remove this export when load_last_inst() is generic */
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index a18afda..6f2d2fb 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -899,11 +899,12 @@ void kvmppc_core_flush_memslot_hv(struct kvm *kvm,
gfn = memslot->base_gfn;
rmapp = memslot->arch.rmap;
+ if (kvm_is_radix(kvm)) {
+ kvmppc_radix_flush_memslot(kvm, memslot);
+ return;
+ }
+
for (n = memslot->npages; n; --n, ++gfn) {
- if (kvm_is_radix(kvm)) {
- kvm_unmap_radix(kvm, memslot, gfn);
- continue;
- }
/*
* Testing the present bit without locking is OK because
* the memslot has been marked invalid already, and hence
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 52711eb..d675ad9 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -958,6 +958,26 @@ long kvmppc_hv_get_dirty_log_radix(struct kvm *kvm,
return 0;
}
+void kvmppc_radix_flush_memslot(struct kvm *kvm,
+ const struct kvm_memory_slot *memslot)
+{
+ unsigned long n;
+ pte_t *ptep;
+ unsigned long gpa;
+ unsigned int shift;
+
+ gpa = memslot->base_gfn << PAGE_SHIFT;
+ spin_lock(&kvm->mmu_lock);
+ for (n = memslot->npages; n; --n) {
+ ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
+ if (ptep && pte_present(*ptep))
+ kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
+ kvm->arch.lpid);
+ gpa += PAGE_SIZE;
+ }
+ spin_unlock(&kvm->mmu_lock);
+}
+
static void add_rmmu_ap_encoding(struct kvm_ppc_rmmu_info *info,
int psize, int *indexp)
{
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index f4fbb7b5..074ff5b 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4384,6 +4384,23 @@ static void kvmppc_core_commit_memory_region_hv(struct kvm *kvm,
*/
if (npages)
atomic64_inc(&kvm->arch.mmio_update);
+
+ /*
+ * For change == KVM_MR_MOVE or KVM_MR_DELETE, higher levels
+ * have already called kvm_arch_flush_shadow_memslot() to
+ * flush shadow mappings. For KVM_MR_CREATE we have no
+ * previous mappings. So the only case to handle is
+ * KVM_MR_FLAGS_ONLY when the KVM_MEM_LOG_DIRTY_PAGES bit
+ * has been changed.
+ * For radix guests, we flush on setting KVM_MEM_LOG_DIRTY_PAGES
+ * to get rid of any THP PTEs in the partition-scoped page tables
+ * so we can track dirtiness at the page level; we flush when
+ * clearing KVM_MEM_LOG_DIRTY_PAGES so that we can go back to
+ * using THP PTEs.
+ */
+ if (change == KVM_MR_FLAGS_ONLY && kvm_is_radix(kvm) &&
+ ((new->flags ^ old->flags) & KVM_MEM_LOG_DIRTY_PAGES))
+ kvmppc_radix_flush_memslot(kvm, old);
}
/*
--
2.7.4
