diff options
Diffstat (limited to 'arch/x86/kvm/vmx/vmenter.S')
| -rw-r--r-- | arch/x86/kvm/vmx/vmenter.S | 51 |
1 files changed, 34 insertions, 17 deletions
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S index bc255d709d8a..4426d34811fc 100644 --- a/arch/x86/kvm/vmx/vmenter.S +++ b/arch/x86/kvm/vmx/vmenter.S @@ -71,6 +71,7 @@ * @regs: unsigned long * (to guest registers) * @flags: VMX_RUN_VMRESUME: use VMRESUME instead of VMLAUNCH * VMX_RUN_SAVE_SPEC_CTRL: save guest SPEC_CTRL into vmx->spec_ctrl + * VMX_RUN_CLEAR_CPU_BUFFERS_FOR_MMIO: vCPU can access host MMIO * * Returns: * 0 on VM-Exit, 1 on VM-Fail @@ -92,7 +93,7 @@ SYM_FUNC_START(__vmx_vcpu_run) /* Save @vmx for SPEC_CTRL handling */ push %_ASM_ARG1 - /* Save @flags for SPEC_CTRL handling */ + /* Save @flags (used for VMLAUNCH vs. VMRESUME and mitigations). */ push %_ASM_ARG3 /* @@ -101,9 +102,6 @@ SYM_FUNC_START(__vmx_vcpu_run) */ push %_ASM_ARG2 - /* Copy @flags to EBX, _ASM_ARG3 is volatile. */ - mov %_ASM_ARG3L, %ebx - lea (%_ASM_SP), %_ASM_ARG2 call vmx_update_host_rsp @@ -118,13 +116,23 @@ SYM_FUNC_START(__vmx_vcpu_run) * and vmentry. */ mov 2*WORD_SIZE(%_ASM_SP), %_ASM_DI - movl VMX_spec_ctrl(%_ASM_DI), %edi - movl PER_CPU_VAR(x86_spec_ctrl_current), %esi - cmp %edi, %esi +#ifdef CONFIG_X86_64 + mov VMX_spec_ctrl(%rdi), %rdx + cmp PER_CPU_VAR(x86_spec_ctrl_current), %rdx je .Lspec_ctrl_done + movl %edx, %eax + shr $32, %rdx +#else + mov VMX_spec_ctrl(%edi), %eax + mov PER_CPU_VAR(x86_spec_ctrl_current), %ecx + xor %eax, %ecx + mov VMX_spec_ctrl + 4(%edi), %edx + mov PER_CPU_VAR(x86_spec_ctrl_current + 4), %edi + xor %edx, %edi + or %edi, %ecx + je .Lspec_ctrl_done +#endif mov $MSR_IA32_SPEC_CTRL, %ecx - xor %edx, %edx - mov %edi, %eax wrmsr .Lspec_ctrl_done: @@ -137,9 +145,6 @@ SYM_FUNC_START(__vmx_vcpu_run) /* Load @regs to RAX. */ mov (%_ASM_SP), %_ASM_AX - /* Check if vmlaunch or vmresume is needed */ - bt $VMX_RUN_VMRESUME_SHIFT, %ebx - /* Load guest registers. Don't clobber flags. */ mov VCPU_RCX(%_ASM_AX), %_ASM_CX mov VCPU_RDX(%_ASM_AX), %_ASM_DX @@ -160,11 +165,23 @@ SYM_FUNC_START(__vmx_vcpu_run) /* Load guest RAX. This kills the @regs pointer! */ mov VCPU_RAX(%_ASM_AX), %_ASM_AX - /* Clobbers EFLAGS.ZF */ - CLEAR_CPU_BUFFERS - - /* Check EFLAGS.CF from the VMX_RUN_VMRESUME bit test above. */ - jnc .Lvmlaunch + /* + * Note, ALTERNATIVE_2 works in reverse order. If CLEAR_CPU_BUF_VM is + * enabled, do VERW unconditionally. If CPU_BUF_VM_MMIO is enabled, + * check @flags to see if the vCPU has access to host MMIO, and if so, + * do VERW. Else, do nothing (no mitigations needed/enabled). + */ + ALTERNATIVE_2 "", \ + __stringify(testl $VMX_RUN_CLEAR_CPU_BUFFERS_FOR_MMIO, WORD_SIZE(%_ASM_SP); \ + jz .Lskip_mmio_verw; \ + VERW; \ + .Lskip_mmio_verw:), \ + X86_FEATURE_CLEAR_CPU_BUF_VM_MMIO, \ + __stringify(VERW), X86_FEATURE_CLEAR_CPU_BUF_VM + + /* Check @flags to see if VMLAUNCH or VMRESUME is needed. */ + testl $VMX_RUN_VMRESUME, WORD_SIZE(%_ASM_SP) + jz .Lvmlaunch /* * After a successful VMRESUME/VMLAUNCH, control flow "magically" |