Commit f7ef2801 authored Oct 28, 2022 by Paolo Bonzini

KVM: SVM: adjust register allocation for __svm_vcpu_run()



32-bit ABI uses RAX/RCX/RDX as its argument registers, so they are in
the way of instructions that hardcode their operands such as RDMSR/WRMSR
or VMLOAD/VMRUN/VMSAVE.

In preparation for moving vmload/vmsave to __svm_vcpu_run(), keep
the pointer to the struct vcpu_svm in %rdi.  In particular, it is now
possible to load svm->vmcb01.pa in %rax without clobbering the struct
vcpu_svm pointer.

No functional change intended.

Cc: stable@vger.kernel.org
Fixes: a149180f ("x86: Add magic AMD return-thunk")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 16fdc1de

arch/x86/kvm/svm/vmenter.S

+19 −19

Original line number	Diff line number	Diff line
		@@ -54,29 +54,29 @@ SYM_FUNC_START(__svm_vcpu_run)
		/* Save @vmcb. */
		push %_ASM_ARG1

		/* Move @svm to RAX. */
		mov %_ASM_ARG2, %_ASM_AX
		/* Move @svm to RDI. */
		mov %_ASM_ARG2, %_ASM_DI

		/* "POP" @vmcb to RAX. */
		pop %_ASM_AX

		/* Load guest registers. */
		mov VCPU_RCX(%_ASM_AX), %_ASM_CX
		mov VCPU_RDX(%_ASM_AX), %_ASM_DX
		mov VCPU_RBX(%_ASM_AX), %_ASM_BX
		mov VCPU_RBP(%_ASM_AX), %_ASM_BP
		mov VCPU_RSI(%_ASM_AX), %_ASM_SI
		mov VCPU_RDI(%_ASM_AX), %_ASM_DI
		mov VCPU_RCX(%_ASM_DI), %_ASM_CX
		mov VCPU_RDX(%_ASM_DI), %_ASM_DX
		mov VCPU_RBX(%_ASM_DI), %_ASM_BX
		mov VCPU_RBP(%_ASM_DI), %_ASM_BP
		mov VCPU_RSI(%_ASM_DI), %_ASM_SI
		#ifdef CONFIG_X86_64
		mov VCPU_R8 (%_ASM_AX), %r8
		mov VCPU_R9 (%_ASM_AX), %r9
		mov VCPU_R10(%_ASM_AX), %r10
		mov VCPU_R11(%_ASM_AX), %r11
		mov VCPU_R12(%_ASM_AX), %r12
		mov VCPU_R13(%_ASM_AX), %r13
		mov VCPU_R14(%_ASM_AX), %r14
		mov VCPU_R15(%_ASM_AX), %r15
		mov VCPU_R8 (%_ASM_DI), %r8
		mov VCPU_R9 (%_ASM_DI), %r9
		mov VCPU_R10(%_ASM_DI), %r10
		mov VCPU_R11(%_ASM_DI), %r11
		mov VCPU_R12(%_ASM_DI), %r12
		mov VCPU_R13(%_ASM_DI), %r13
		mov VCPU_R14(%_ASM_DI), %r14
		mov VCPU_R15(%_ASM_DI), %r15
		#endif

		/* "POP" @vmcb to RAX. */
		pop %_ASM_AX
		mov VCPU_RDI(%_ASM_DI), %_ASM_DI

		/* Enter guest mode */
		sti