98 lines
3.3 KiB
Diff
98 lines
3.3 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Jim Mattson <jmattson@google.com>
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Date: Wed, 3 Jan 2018 14:31:38 -0800
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Subject: [PATCH] kvm: vmx: Scrub hardware GPRs at VM-exit
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Guest GPR values are live in the hardware GPRs at VM-exit. Do not
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leave any guest values in hardware GPRs after the guest GPR values are
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saved to the vcpu_vmx structure.
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This is a partial mitigation for CVE 2017-5715 and CVE 2017-5753.
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Specifically, it defeats the Project Zero PoC for CVE 2017-5715.
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Suggested-by: Eric Northup <digitaleric@google.com>
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Signed-off-by: Jim Mattson <jmattson@google.com>
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Reviewed-by: Eric Northup <digitaleric@google.com>
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Reviewed-by: Benjamin Serebrin <serebrin@google.com>
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Reviewed-by: Andrew Honig <ahonig@google.com>
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[Paolo: Add AMD bits, Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>]
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kvm/svm.c | 19 +++++++++++++++++++
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arch/x86/kvm/vmx.c | 14 +++++++++++++-
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2 files changed, 32 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
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index af09baa3d736..92cd94d51e1f 100644
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--- a/arch/x86/kvm/svm.c
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+++ b/arch/x86/kvm/svm.c
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@@ -4924,6 +4924,25 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
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"mov %%r13, %c[r13](%[svm]) \n\t"
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"mov %%r14, %c[r14](%[svm]) \n\t"
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"mov %%r15, %c[r15](%[svm]) \n\t"
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+#endif
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+ /*
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+ * Clear host registers marked as clobbered to prevent
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+ * speculative use.
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+ */
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+ "xor %%" _ASM_BX ", %%" _ASM_BX " \n\t"
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+ "xor %%" _ASM_CX ", %%" _ASM_CX " \n\t"
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+ "xor %%" _ASM_DX ", %%" _ASM_DX " \n\t"
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+ "xor %%" _ASM_SI ", %%" _ASM_SI " \n\t"
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+ "xor %%" _ASM_DI ", %%" _ASM_DI " \n\t"
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+#ifdef CONFIG_X86_64
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+ "xor %%r8, %%r8 \n\t"
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+ "xor %%r9, %%r9 \n\t"
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+ "xor %%r10, %%r10 \n\t"
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+ "xor %%r11, %%r11 \n\t"
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+ "xor %%r12, %%r12 \n\t"
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+ "xor %%r13, %%r13 \n\t"
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+ "xor %%r14, %%r14 \n\t"
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+ "xor %%r15, %%r15 \n\t"
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#endif
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"pop %%" _ASM_BP
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:
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diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
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index d61986a36575..9b4256fd589a 100644
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--- a/arch/x86/kvm/vmx.c
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+++ b/arch/x86/kvm/vmx.c
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@@ -9140,6 +9140,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
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/* Save guest registers, load host registers, keep flags */
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"mov %0, %c[wordsize](%%" _ASM_SP ") \n\t"
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"pop %0 \n\t"
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+ "setbe %c[fail](%0)\n\t"
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"mov %%" _ASM_AX ", %c[rax](%0) \n\t"
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"mov %%" _ASM_BX ", %c[rbx](%0) \n\t"
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__ASM_SIZE(pop) " %c[rcx](%0) \n\t"
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@@ -9156,12 +9157,23 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
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"mov %%r13, %c[r13](%0) \n\t"
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"mov %%r14, %c[r14](%0) \n\t"
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"mov %%r15, %c[r15](%0) \n\t"
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+ "xor %%r8d, %%r8d \n\t"
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+ "xor %%r9d, %%r9d \n\t"
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+ "xor %%r10d, %%r10d \n\t"
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+ "xor %%r11d, %%r11d \n\t"
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+ "xor %%r12d, %%r12d \n\t"
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+ "xor %%r13d, %%r13d \n\t"
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+ "xor %%r14d, %%r14d \n\t"
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+ "xor %%r15d, %%r15d \n\t"
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#endif
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"mov %%cr2, %%" _ASM_AX " \n\t"
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"mov %%" _ASM_AX ", %c[cr2](%0) \n\t"
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+ "xor %%eax, %%eax \n\t"
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+ "xor %%ebx, %%ebx \n\t"
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+ "xor %%esi, %%esi \n\t"
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+ "xor %%edi, %%edi \n\t"
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"pop %%" _ASM_BP "; pop %%" _ASM_DX " \n\t"
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- "setbe %c[fail](%0) \n\t"
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".pushsection .rodata \n\t"
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".global vmx_return \n\t"
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"vmx_return: " _ASM_PTR " 2b \n\t"
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--
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2.14.2
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