In the case where the host kernel is using a 64kB base page size and
the guest uses a 4k HPTE (hashed page table entry) to map an emulated
MMIO device, we were calculating the guest physical address wrongly.
We were calculating a gfn as the guest physical address shifted right
16 bits (PAGE_SHIFT) but then only adding back in 12 bits from the
effective address, since the HPTE had a 4k page size. Thus the gpa
reported to userspace was missing 4 bits.
Instead, we now compute the guest physical address from the HPTE
without reference to the host page size, and then compute the gfn
by shifting the gpa right PAGE_SHIFT bits.
Reported-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
---
arch/powerpc/kvm/book3s_64_mmu_hv.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index f598366..7a4aae9 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -571,7 +571,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
struct kvm *kvm = vcpu->kvm;
unsigned long *hptep, hpte[3], r;
unsigned long mmu_seq, psize, pte_size;
- unsigned long gfn, hva, pfn;
+ unsigned long gpa, gfn, hva, pfn;
struct kvm_memory_slot *memslot;
unsigned long *rmap;
struct revmap_entry *rev;
@@ -609,15 +609,14 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
/* Translate the logical address and get the page */
psize = hpte_page_size(hpte[0], r);
- gfn = hpte_rpn(r, psize);
+ gpa = (r & HPTE_R_RPN & ~(psize - 1)) | (ea & (psize - 1));
+ gfn = gpa >> PAGE_SHIFT;
memslot = gfn_to_memslot(kvm, gfn);
/* No memslot means it's an emulated MMIO region */
- if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID)) {
- unsigned long gpa = (gfn << PAGE_SHIFT) | (ea & (psize - 1));
+ if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
return kvmppc_hv_emulate_mmio(run, vcpu, gpa, ea,
dsisr & DSISR_ISSTORE);
- }
if (!kvm->arch.using_mmu_notifiers)
return -EFAULT; /* should never get here */
--
1.7.10
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