From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 1/5] KVM: vmx: fix ept reserved bits for 1-GByte page Date: Mon, 18 Aug 2014 12:18:59 +0200 Message-ID: <53F1D313.5010108@redhat.com> References: <1408355431-115633-1-git-send-email-wanpeng.li@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Cc: Gleb Natapov , hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Wanpeng Li Return-path: In-Reply-To: <1408355431-115633-1-git-send-email-wanpeng.li@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Il 18/08/2014 11:50, Wanpeng Li ha scritto: > EPT misconfig handler in kvm will check which reason lead to EPT > misconfiguration after vmexit. One of the reasons is that an EPT > paging-structure entry is configured with settings reserved for > future functionality. However, the handler can't identify if > paging-structure entry of reserved bits for 1-GByte page are > configured, since PDPTE which point to 1-GByte page will reserve > bits 29:12 instead of bits 7:3 which are reserved for PDPTE that > references an EPT Page Directory. This patch fix it by reserve > bits 29:12 for 1-GByte page. > > Signed-off-by: Wanpeng Li > --- > arch/x86/kvm/vmx.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index bfe11cf..71cbee5 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -5521,9 +5521,14 @@ static u64 ept_rsvd_mask(u64 spte, int level) > for (i = 51; i > boot_cpu_data.x86_phys_bits; i--) > mask |= (1ULL << i); > > - if (level > 2) > - /* bits 7:3 reserved */ > - mask |= 0xf8; > + if (level > 2) { level can be 4 here. You have to return 0xf8 for level == 4. The same "if" statement then can cover both 2MB and 1GB pages, like if (spte & (1ULL << 7)) /* 1GB/2MB page, bits 29:12 or 20:12 reserved respectively */ mask |= (PAGE_SIZE << ((level - 1) * 9)) - PAGE_SIZE; else /* bits 6:3 reserved */ mask |= 0x78; > - if (level == 1 || (level == 2 && (spte & (1ULL << 7)))) { > + if (level == 1 || ((level == 3 || level == 2) > + && (spte & (1ULL << 7)))) { This condition can be simplified by checking the return value of ept_rsvd_mask. If it includes 0x38, this is a large page. Otherwise it is a leaf page and you can go down the "if". Paolo > u64 ept_mem_type = (spte & 0x38) >> 3; > > if (ept_mem_type == 2 || ept_mem_type == 3 || >