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- From 711a55c9d58955a2bfca89cd25935ca607e49bc0 Mon Sep 17 00:00:00 2001
- From: Jim Mattson <[email protected]>
- Date: Wed, 3 Jan 2018 14:31:38 -0800
- Subject: [PATCH 232/241] kvm: vmx: Scrub hardware GPRs at VM-exit
- MIME-Version: 1.0
- Content-Type: text/plain; charset=UTF-8
- Content-Transfer-Encoding: 8bit
- Guest GPR values are live in the hardware GPRs at VM-exit. Do not
- leave any guest values in hardware GPRs after the guest GPR values are
- saved to the vcpu_vmx structure.
- This is a partial mitigation for CVE 2017-5715 and CVE 2017-5753.
- Specifically, it defeats the Project Zero PoC for CVE 2017-5715.
- Suggested-by: Eric Northup <[email protected]>
- Signed-off-by: Jim Mattson <[email protected]>
- Reviewed-by: Eric Northup <[email protected]>
- Reviewed-by: Benjamin Serebrin <[email protected]>
- Reviewed-by: Andrew Honig <[email protected]>
- [Paolo: Add AMD bits, Signed-off-by: Tom Lendacky <[email protected]>]
- Signed-off-by: Paolo Bonzini <[email protected]>
- Signed-off-by: Fabian Grünbichler <[email protected]>
- ---
- arch/x86/kvm/svm.c | 19 +++++++++++++++++++
- arch/x86/kvm/vmx.c | 14 +++++++++++++-
- 2 files changed, 32 insertions(+), 1 deletion(-)
- diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
- index af09baa3d736..92cd94d51e1f 100644
- --- a/arch/x86/kvm/svm.c
- +++ b/arch/x86/kvm/svm.c
- @@ -4924,6 +4924,25 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
- "mov %%r13, %c[r13](%[svm]) \n\t"
- "mov %%r14, %c[r14](%[svm]) \n\t"
- "mov %%r15, %c[r15](%[svm]) \n\t"
- +#endif
- + /*
- + * Clear host registers marked as clobbered to prevent
- + * speculative use.
- + */
- + "xor %%" _ASM_BX ", %%" _ASM_BX " \n\t"
- + "xor %%" _ASM_CX ", %%" _ASM_CX " \n\t"
- + "xor %%" _ASM_DX ", %%" _ASM_DX " \n\t"
- + "xor %%" _ASM_SI ", %%" _ASM_SI " \n\t"
- + "xor %%" _ASM_DI ", %%" _ASM_DI " \n\t"
- +#ifdef CONFIG_X86_64
- + "xor %%r8, %%r8 \n\t"
- + "xor %%r9, %%r9 \n\t"
- + "xor %%r10, %%r10 \n\t"
- + "xor %%r11, %%r11 \n\t"
- + "xor %%r12, %%r12 \n\t"
- + "xor %%r13, %%r13 \n\t"
- + "xor %%r14, %%r14 \n\t"
- + "xor %%r15, %%r15 \n\t"
- #endif
- "pop %%" _ASM_BP
- :
- diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
- index d61986a36575..9b4256fd589a 100644
- --- a/arch/x86/kvm/vmx.c
- +++ b/arch/x86/kvm/vmx.c
- @@ -9140,6 +9140,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
- /* Save guest registers, load host registers, keep flags */
- "mov %0, %c[wordsize](%%" _ASM_SP ") \n\t"
- "pop %0 \n\t"
- + "setbe %c[fail](%0)\n\t"
- "mov %%" _ASM_AX ", %c[rax](%0) \n\t"
- "mov %%" _ASM_BX ", %c[rbx](%0) \n\t"
- __ASM_SIZE(pop) " %c[rcx](%0) \n\t"
- @@ -9156,12 +9157,23 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
- "mov %%r13, %c[r13](%0) \n\t"
- "mov %%r14, %c[r14](%0) \n\t"
- "mov %%r15, %c[r15](%0) \n\t"
- + "xor %%r8d, %%r8d \n\t"
- + "xor %%r9d, %%r9d \n\t"
- + "xor %%r10d, %%r10d \n\t"
- + "xor %%r11d, %%r11d \n\t"
- + "xor %%r12d, %%r12d \n\t"
- + "xor %%r13d, %%r13d \n\t"
- + "xor %%r14d, %%r14d \n\t"
- + "xor %%r15d, %%r15d \n\t"
- #endif
- "mov %%cr2, %%" _ASM_AX " \n\t"
- "mov %%" _ASM_AX ", %c[cr2](%0) \n\t"
-
- + "xor %%eax, %%eax \n\t"
- + "xor %%ebx, %%ebx \n\t"
- + "xor %%esi, %%esi \n\t"
- + "xor %%edi, %%edi \n\t"
- "pop %%" _ASM_BP "; pop %%" _ASM_DX " \n\t"
- - "setbe %c[fail](%0) \n\t"
- ".pushsection .rodata \n\t"
- ".global vmx_return \n\t"
- "vmx_return: " _ASM_PTR " 2b \n\t"
- --
- 2.14.2
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