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KVM: PPC: Book3S HV: Flush guest mappings when turning dirty tracking on/off

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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@ozlabs.org>
Reviewed-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Paul Mackerras 2018-12-12 15:17:17 +11:00
parent c43c3a8683
commit 5af3e9d06d
4 changed files with 44 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/include/asm/kvm_book3s.h
View File

@ -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 */

9
arch/powerpc/kvm/book3s_64_mmu_hv.c
View File

@ -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

20
arch/powerpc/kvm/book3s_64_mmu_radix.c
View File

@ -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)
{

17
arch/powerpc/kvm/book3s_hv.c
View File

@ -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);
}
/*