patches/kernel/0234-kvm-vmx-Scrub-hardware-GPRs-at-VM-exit.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Jim Mattson <jmattson@google.com>
   3 Date: Wed, 3 Jan 2018 14:31:38 -0800
   4 Subject: [PATCH] kvm: vmx: Scrub hardware GPRs at VM-exit
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 Guest GPR values are live in the hardware GPRs at VM-exit.  Do not
  10 leave any guest values in hardware GPRs after the guest GPR values are
  11 saved to the vcpu_vmx structure.
  12
  13 This is a partial mitigation for CVE 2017-5715 and CVE 2017-5753.
  14 Specifically, it defeats the Project Zero PoC for CVE 2017-5715.
  15
  16 Suggested-by: Eric Northup <digitaleric@google.com>
  17 Signed-off-by: Jim Mattson <jmattson@google.com>
  18 Reviewed-by: Eric Northup <digitaleric@google.com>
  19 Reviewed-by: Benjamin Serebrin <serebrin@google.com>
  20 Reviewed-by: Andrew Honig <ahonig@google.com>
  21 [Paolo: Add AMD bits, Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>]
  22 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
  23 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  24 ---
  25  arch/x86/kvm/svm.c | 19 +++++++++++++++++++
  26  arch/x86/kvm/vmx.c | 14 +++++++++++++-
  27  2 files changed, 32 insertions(+), 1 deletion(-)
  28
  29 diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
  30 index af09baa3d736..92cd94d51e1f 100644
  31 --- a/arch/x86/kvm/svm.c
  32 +++ b/arch/x86/kvm/svm.c
  33 @@ -4924,6 +4924,25 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
  34                 "mov %%r13, %c[r13](%[svm]) \n\t"
  35                 "mov %%r14, %c[r14](%[svm]) \n\t"
  36                 "mov %%r15, %c[r15](%[svm]) \n\t"
  37 +#endif
  38 +               /*
  39 +               * Clear host registers marked as clobbered to prevent
  40 +               * speculative use.
  41 +               */
  42 +               "xor %%" _ASM_BX ", %%" _ASM_BX " \n\t"
  43 +               "xor %%" _ASM_CX ", %%" _ASM_CX " \n\t"
  44 +               "xor %%" _ASM_DX ", %%" _ASM_DX " \n\t"
  45 +               "xor %%" _ASM_SI ", %%" _ASM_SI " \n\t"
  46 +               "xor %%" _ASM_DI ", %%" _ASM_DI " \n\t"
  47 +#ifdef CONFIG_X86_64
  48 +               "xor %%r8, %%r8 \n\t"
  49 +               "xor %%r9, %%r9 \n\t"
  50 +               "xor %%r10, %%r10 \n\t"
  51 +               "xor %%r11, %%r11 \n\t"
  52 +               "xor %%r12, %%r12 \n\t"
  53 +               "xor %%r13, %%r13 \n\t"
  54 +               "xor %%r14, %%r14 \n\t"
  55 +               "xor %%r15, %%r15 \n\t"
  56  #endif
  57                 "pop %%" _ASM_BP
  58                 :
  59 diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
  60 index d61986a36575..9b4256fd589a 100644
  61 --- a/arch/x86/kvm/vmx.c
  62 +++ b/arch/x86/kvm/vmx.c
  63 @@ -9140,6 +9140,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
  64                 /* Save guest registers, load host registers, keep flags */
  65                 "mov %0, %c[wordsize](%%" _ASM_SP ") \n\t"
  66                 "pop %0 \n\t"
  67 +               "setbe %c[fail](%0)\n\t"
  68                 "mov %%" _ASM_AX ", %c[rax](%0) \n\t"
  69                 "mov %%" _ASM_BX ", %c[rbx](%0) \n\t"
  70                 __ASM_SIZE(pop) " %c[rcx](%0) \n\t"
  71 @@ -9156,12 +9157,23 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
  72                 "mov %%r13, %c[r13](%0) \n\t"
  73                 "mov %%r14, %c[r14](%0) \n\t"
  74                 "mov %%r15, %c[r15](%0) \n\t"
  75 +               "xor %%r8d,  %%r8d \n\t"
  76 +               "xor %%r9d,  %%r9d \n\t"
  77 +               "xor %%r10d, %%r10d \n\t"
  78 +               "xor %%r11d, %%r11d \n\t"
  79 +               "xor %%r12d, %%r12d \n\t"
  80 +               "xor %%r13d, %%r13d \n\t"
  81 +               "xor %%r14d, %%r14d \n\t"
  82 +               "xor %%r15d, %%r15d \n\t"
  83  #endif
  84                 "mov %%cr2, %%" _ASM_AX "   \n\t"
  85                 "mov %%" _ASM_AX ", %c[cr2](%0) \n\t"
  86
  87 +               "xor %%eax, %%eax \n\t"
  88 +               "xor %%ebx, %%ebx \n\t"
  89 +               "xor %%esi, %%esi \n\t"
  90 +               "xor %%edi, %%edi \n\t"
  91                 "pop  %%" _ASM_BP "; pop  %%" _ASM_DX " \n\t"
  92 -               "setbe %c[fail](%0) \n\t"
  93                 ".pushsection .rodata \n\t"
  94                 ".global vmx_return \n\t"
  95                 "vmx_return: " _ASM_PTR " 2b \n\t"
  96 --
  97 2.14.2
  98