Commit 5a7a6477 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: VMX: Access @flags as a 32-bit value in __vmx_vcpu_run() 



Access @flags using 32-bit operands when saving and testing @flags for
VMX_RUN_VMRESUME, as using 8-bit operands is unnecessarily fragile due
to relying on VMX_RUN_VMRESUME being in bits 0-7.  The behavior of
treating @flags a single byte is a holdover from when the param was
"bool launched", i.e. is not deliberate.

Cc: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Link: https://lore.kernel.org/r/20221119003747.2615229-1-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 7cb79f43

arch/x86/kvm/vmx/vmenter.S

+4 −4
Original line number Diff line number Diff line
@@ -69,8 +69,8 @@ SYM_FUNC_START(__vmx_vcpu_run) 
	 */

	push %_ASM_ARG2



	/* Copy @flags to BL, _ASM_ARG3 is volatile. */

	mov %_ASM_ARG3B, %bl

	/* Copy @flags to EBX, _ASM_ARG3 is volatile. */

	mov %_ASM_ARG3L, %ebx



	lea (%_ASM_SP), %_ASM_ARG2

	call vmx_update_host_rsp
@@ -106,7 +106,7 @@ SYM_FUNC_START(__vmx_vcpu_run) 
	mov (%_ASM_SP), %_ASM_AX



	/* Check if vmlaunch or vmresume is needed */

	testb $VMX_RUN_VMRESUME, %bl

	test $VMX_RUN_VMRESUME, %ebx



	/* Load guest registers.  Don't clobber flags. */

	mov VCPU_RCX(%_ASM_AX), %_ASM_CX
@@ -128,7 +128,7 @@ SYM_FUNC_START(__vmx_vcpu_run) 
	/* Load guest RAX.  This kills the @regs pointer! */

	mov VCPU_RAX(%_ASM_AX), %_ASM_AX



	/* Check EFLAGS.ZF from 'testb' above */

	/* Check EFLAGS.ZF from 'test VMX_RUN_VMRESUME' above */

	jz .Lvmlaunch



	/*