From 41e3025eacd6daafc40c3e7850fbcabc8b847805 Mon Sep 17 00:00:00 2001 From: Xiao Guangrong Date: Wed, 5 Aug 2015 12:04:19 +0800 Subject: [PATCH] KVM: MMU: fix validation of mmio page fault commit 6f691251c0350ac52a007c54bf3ef62e9d8cdc5e upstream. We got the bug that qemu complained with "KVM: unknown exit, hardware reason 31" and KVM shown these info: [84245.284948] EPT: Misconfiguration. [84245.285056] EPT: GPA: 0xfeda848 [84245.285154] ept_misconfig_inspect_spte: spte 0x5eaef50107 level 4 [84245.285344] ept_misconfig_inspect_spte: spte 0x5f5fadc107 level 3 [84245.285532] ept_misconfig_inspect_spte: spte 0x5141d18107 level 2 [84245.285723] ept_misconfig_inspect_spte: spte 0x52e40dad77 level 1 This is because we got a mmio #PF and the handler see the mmio spte becomes normal (points to the ram page) However, this is valid after introducing fast mmio spte invalidation which increases the generation-number instead of zapping mmio sptes, a example is as follows: 1. QEMU drops mmio region by adding a new memslot 2. invalidate all mmio sptes 3. VCPU 0 VCPU 1 access the invalid mmio spte access the region originally was MMIO before set the spte to the normal ram map mmio #PF check the spte and see it becomes normal ram mapping !!! This patch fixes the bug just by dropping the check in mmio handler, it's good for backport. Full check will be introduced in later patches Reported-by: Pavel Shirshov Tested-by: Pavel Shirshov Signed-off-by: Xiao Guangrong Signed-off-by: Paolo Bonzini [bwh: Backported to 3.2: error code from handle_mmio_page_fault_common() was not named] Signed-off-by: Ben Hutchings --- Reading git-format-patch failed