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Commit f1727b49 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: nVMX: Capture VM-Fail to a local var in nested_vmx_check_vmentry_hw() 



Unlike the primary vCPU-run flow, the nested early checks code doesn't
actually want to propagate VM-Fail back to 'vmx'.  Yay copy+paste.

In additional to eliminating the need to clear vmx->fail before
returning, using a local boolean also drops a reference to 'vmx' in the
asm blob.  Dropping the reference to 'vmx' will save a register in the
long run as future patches will shift all pointer references from 'vmx'
to 'vmx->loaded_vmcs'.

Fixes: 52017608 ("KVM: nVMX: add option to perform early consistency checks via H/W")
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 6c1e7e5b

arch/x86/kvm/vmx/nested.c

+10 −6
Original line number Diff line number Diff line
@@ -2718,6 +2718,7 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) 
{

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	unsigned long cr3, cr4;

	bool vm_fail;



	if (!nested_early_check)

		return 0;
@@ -2763,14 +2764,18 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) 
		/* Check if vmlaunch or vmresume is needed */

		"cmpb $0, %c[launched](%% " _ASM_CX")\n\t"



		/*

		 * VMLAUNCH and VMRESUME clear RFLAGS.{CF,ZF} on VM-Exit, set

		 * RFLAGS.CF on VM-Fail Invalid and set RFLAGS.ZF on VM-Fail

		 * Valid.  vmx_vmenter() directly "returns" RFLAGS, and so the

		 * results of VM-Enter is captured via SETBE to vm_fail.

		 */

		"call vmx_vmenter\n\t"



		/* Set vmx->fail accordingly */

		"setbe %c[fail](%% " _ASM_CX")\n\t"

	      : ASM_CALL_CONSTRAINT

		"setbe %[fail]\n\t"

	      : ASM_CALL_CONSTRAINT, [fail]"=qm"(vm_fail)

	      : "c"(vmx), "d"((unsigned long)HOST_RSP),

		[launched]"i"(offsetof(struct vcpu_vmx, __launched)),

		[fail]"i"(offsetof(struct vcpu_vmx, fail)),

		[host_rsp]"i"(offsetof(struct vcpu_vmx, host_rsp)),

		[wordsize]"i"(sizeof(ulong))

	      : "cc", "memory"
@@ -2783,10 +2788,9 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu) 
	if (vmx->msr_autoload.guest.nr)

		vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_autoload.guest.nr);



	if (vmx->fail) {

	if (vm_fail) {

		WARN_ON_ONCE(vmcs_read32(VM_INSTRUCTION_ERROR) !=

			     VMXERR_ENTRY_INVALID_CONTROL_FIELD);

		vmx->fail = 0;

		return 1;

	}