From 85c8555ff07ef09261bd50d603cd4290cff5a8cc Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 12 Sep 2014 15:16:00 +0200 Subject: [PATCH] KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn() Read-only memory ranges may be backed by the zero page, so avoid misidentifying it a a MMIO pfn. This fixes another issue I identified when testing QEMU+KVM_UEFI, where a read to an uninitialized emulated NOR flash brought in the zero page, but mapped as a read-write device region, because kvm_is_mmio_pfn() misidentifies it as a MMIO pfn due to its PG_reserved bit being set. Signed-off-by: Ard Biesheuvel Fixes: b88657674d39 ("ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping") Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 33712fb26eb1..96ec6226e4ab 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -110,7 +110,7 @@ static bool largepages_enabled = true; bool kvm_is_mmio_pfn(pfn_t pfn) { if (pfn_valid(pfn)) - return PageReserved(pfn_to_page(pfn)); + return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn)); return true; } -- GitLab