This is a note to let you know that I've just added the patch titled

kvm: vmx: Scrub hardware GPRs at VM-exit

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kvm-vmx-scrub-hardware-gprs-at-vm-exit.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 0cb5b30698fdc8f6b4646012e3acb4ddce430788 Mon Sep 17 00:00:00 2001

From: Jim Mattson jmattson@google.com Date: Wed, 3 Jan 2018 14:31:38 -0800 Subject: kvm: vmx: Scrub hardware GPRs at VM-exit

From: Jim Mattson jmattson@google.com

commit 0cb5b30698fdc8f6b4646012e3acb4ddce430788 upstream.

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 digitaleric@google.com Signed-off-by: Jim Mattson jmattson@google.com Reviewed-by: Eric Northup digitaleric@google.com Reviewed-by: Benjamin Serebrin serebrin@google.com Reviewed-by: Andrew Honig ahonig@google.com [Paolo: Add AMD bits, Signed-off-by: Tom Lendacky thomas.lendacky@amd.com] Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kvm/svm.c | 19 +++++++++++++++++++ arch/x86/kvm/vmx.c | 14 +++++++++++++- 2 files changed, 32 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -3856,6 +3856,25 @@ static void svm_vcpu_run(struct kvm_vcpu "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 : : [svm]"a"(svm), --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -8623,6 +8623,7 @@ static void __noclone vmx_vcpu_run(struc /* 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" @@ -8639,12 +8640,23 @@ static void __noclone vmx_vcpu_run(struc "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"

Patches currently in stable-queue which might be from jmattson@google.com are

queue-4.4/kvm-vmx-scrub-hardware-gprs-at-vm-exit.patch