queue-5.0/kvm-vmx-save-rsi-to-an-unused-output-in-the-vcpu-run-asm-blob.patch

   1 From f3689e3f17f064fd4cd5f0cb01ae2395c94f39d9 Mon Sep 17 00:00:00 2001
   2 From: Sean Christopherson <sean.j.christopherson@intel.com>
   3 Date: Fri, 25 Jan 2019 07:40:52 -0800
   4 Subject: KVM: VMX: Save RSI to an unused output in the vCPU-run asm blob
   5
   6 From: Sean Christopherson <sean.j.christopherson@intel.com>
   7
   8 commit f3689e3f17f064fd4cd5f0cb01ae2395c94f39d9 upstream.
   9
  10 RSI is clobbered by the vCPU-run asm blob, but it's not marked as such,
  11 probably because GCC doesn't let you mark inputs as clobbered.  "Save"
  12 RSI to a dummy output so that GCC recognizes it as being clobbered.
  13
  14 Fixes: 773e8a0425c9 ("x86/kvm: use Enlightened VMCS when running on Hyper-V")
  15 Reviewed-by: Jim Mattson <jmattson@google.com>
  16 Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
  17 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
  18 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  19
  20 ---
  21  arch/x86/kvm/vmx/vmx.c |    2 +-
  22  1 file changed, 1 insertion(+), 1 deletion(-)
  23
  24 --- a/arch/x86/kvm/vmx/vmx.c
  25 +++ b/arch/x86/kvm/vmx/vmx.c
  26 @@ -6465,7 +6465,7 @@ static void __vmx_vcpu_run(struct kvm_vc
  27                 "xor %%edi, %%edi \n\t"
  28                 "xor %%ebp, %%ebp \n\t"
  29                 "pop  %%" _ASM_BP "; pop  %%" _ASM_DX " \n\t"
  30 -             : ASM_CALL_CONSTRAINT
  31 +             : ASM_CALL_CONSTRAINT, "=S"((int){0})
  32               : "c"(vmx), "d"((unsigned long)HOST_RSP), "S"(evmcs_rsp),
  33                 [launched]"i"(offsetof(struct vcpu_vmx, __launched)),
  34                 [fail]"i"(offsetof(struct vcpu_vmx, fail)),