From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtp3PIjTaGew+gZ5Ux8+dWOFAwJ7yEGlnwoAFuZHOuecTTqPmPMII9HpArDch0wCem1ULhA ARC-Seal: i=1; a=rsa-sha256; t=1521215039; cv=none; d=google.com; s=arc-20160816; b=K0Rb3u+VVxKA0+Cl/0X51QA+yHmMKBXN1J+HYnY9Pz8RrJdPHYudN+/LmvfQylDXat 0FlNU3B84fiHSxWATlEmd3RPD+Nt5j6fqg03cSiVdmG77q6BlyQ087wNOUuXjtTudzqj vzA0aKM0zjL7THkAmeeJ7/RwCwg180265HzhSpmu+mtnzbRRTe9wttmTg6plTCqLdlyL vxJqVf7UvoiUI1dfWuzu1MiWUcBmcz4e5RsUX65qFpqyJQpcqqHIAJBh/jEIL1eq9Isv 31RlYA8myPvdFq3njBGrHrHGDv1mCONR1UFAheUpJJoz7zUadxOVeXJFfR1XrQHA3z3b T/sA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=5obkeADDQpkraRprRovI4tNi7ZNZkXLdVEw8z5/OfhM=; b=VnivqwBDNlOC0bZQ4vcRDT0hb8lc1UHjxSliq49fB0E+xKcTonQJtv5HPPNjtI13TO B8O/6/JsvbIAFvgy3S4z//ZphRvuFDwYtUwtnctcZRrcYzFTG6KNaG7YdtrD7L6LyDmS pntO1qrAnAUipdmV27M4NwcI0lXm5FiSmBlMIGBIfFI/zyTvF537pmtdme3lZ5jdeebe 4frySfDNEYMNMncrltKU632SXCgerj4u0Zhx6EUwxGsnHgQp784srCA75MVcq+QcnQd2 yuCj7lUBhmT9gB3LazW5opkzUeYBQKz9d5p7CIYZBwZGXvNZijKD05Vb72NreOplXy0B TNMw== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Joerg Roedel , Borislav Petkov , Tom Lendacky , x86@kernel.org, kvm@vger.kernel.org, Brijesh Singh , Sasha Levin Subject: [PATCH 4.15 079/128] KVM: X86: Restart the guest when insn_len is zero and SEV is enabled Date: Fri, 16 Mar 2018 16:23:40 +0100 Message-Id: <20180316152340.594456442@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180316152336.199007505@linuxfoundation.org> References: <20180316152336.199007505@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1595109581775312555?= X-GMAIL-MSGID: =?utf-8?q?1595109581775312555?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Brijesh Singh [ Upstream commit 00b10fe1046c4b2232097a7ffaa9238c7e479388 ] On AMD platforms, under certain conditions insn_len may be zero on #NPF. This can happen if a guest gets a page-fault on data access but the HW table walker is not able to read the instruction page (e.g instruction page is not present in memory). Typically, when insn_len is zero, x86_emulate_instruction() walks the guest page table and fetches the instruction bytes from guest memory. When SEV is enabled, the guest memory is encrypted with guest-specific key hence hypervisor will not able to fetch the instruction bytes. In those cases we simply restart the guest. I have encountered this issue when running kernbench inside the guest. Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Joerg Roedel Cc: Borislav Petkov Cc: Tom Lendacky Cc: x86@kernel.org Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Brijesh Singh Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu.c | 10 ++++++++++ arch/x86/kvm/svm.c | 6 ++++-- 2 files changed, 14 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4951,6 +4951,16 @@ int kvm_mmu_page_fault(struct kvm_vcpu * if (mmio_info_in_cache(vcpu, cr2, direct)) emulation_type = 0; emulate: + /* + * On AMD platforms, under certain conditions insn_len may be zero on #NPF. + * This can happen if a guest gets a page-fault on data access but the HW + * table walker is not able to read the instruction page (e.g instruction + * page is not present in memory). In those cases we simply restart the + * guest. + */ + if (unlikely(insn && !insn_len)) + return 1; + er = x86_emulate_instruction(vcpu, cr2, emulation_type, insn, insn_len); switch (er) { --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2178,7 +2178,8 @@ static int pf_interception(struct vcpu_s u64 error_code = svm->vmcb->control.exit_info_1; return kvm_handle_page_fault(&svm->vcpu, error_code, fault_address, - svm->vmcb->control.insn_bytes, + static_cpu_has(X86_FEATURE_DECODEASSISTS) ? + svm->vmcb->control.insn_bytes : NULL, svm->vmcb->control.insn_len); } @@ -2189,7 +2190,8 @@ static int npf_interception(struct vcpu_ trace_kvm_page_fault(fault_address, error_code); return kvm_mmu_page_fault(&svm->vcpu, fault_address, error_code, - svm->vmcb->control.insn_bytes, + static_cpu_has(X86_FEATURE_DECODEASSISTS) ? + svm->vmcb->control.insn_bytes : NULL, svm->vmcb->control.insn_len); }