| Message ID | 20200416035358.261056-1-david@gibson.dropbear.id.au (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | KVM: PPC: Handle non-present PTEs in kvmppc_book3s_hv_page_fault() | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (a9aa21d05c33c556e48c5062b6632a9b94906570) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | warning | Upstream build failed, couldn't test patch |
| snowpatch_ozlabs/checkpatch | warning | total: 1 errors, 0 warnings, 0 checks, 11 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch fixes a commit that hasn't been released yet |
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 6404df613ea3..394fca8e630a 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -616,6 +616,11 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, } pte = *ptep; local_irq_enable(); + if (!pte_present(pte)) { + if (page) + put_page(page); + return RESUME_GUEST; + } hpa = pte_pfn(pte) << PAGE_SHIFT; pte_size = PAGE_SIZE; if (shift)
Since cd758a9b57ee "KVM: PPC: Book3S HV: Use __gfn_to_pfn_memslot in HPT page fault handler", it's been possible in fairly rare circumstances to load a non-present PTE in kvmppc_book3s_hv_page_fault() when running a guest on a POWER8 host. Because that case wasn't checked for, we could misinterpret the non-present PTE as being a cache-inhibited PTE. That could mismatch with the corresponding hash PTE, which would cause the function to fail with -EFAULT a little further down. That would propagate up to the KVM_RUN ioctl() generally causing the KVM userspace (usually qemu) to fall over. This addresses the problem by catching that case and returning to the guest instead. Fixes: cd758a9b57ee "KVM: PPC: Book3S HV: Use __gfn_to_pfn_memslot in HPT page fault handler" Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1820402 Suggested-by: Paul Mackerras <paulus@samba.org> Signed-off-by: David Gibson <david@gibson.dropbear.id.au> --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 5 +++++ 1 file changed, 5 insertions(+)