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Commit 7846b311 authored by Dave Martin's avatar Dave Martin Committed by Marc Zyngier
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KVM: arm64: Fold redundant exit code checks out of fixup_guest_exit() 



The entire tail of fixup_guest_exit() is contained in if statements
of the form if (x && *exit_code == ARM_EXCEPTION_TRAP).  As a result,
we can check just once and bail out of the function early, allowing
the remaining if conditions to be simplified.

The only awkward case is where *exit_code is changed to
ARM_EXCEPTION_EL1_SERROR in the case of an illegal GICv2 CPU
interface access: in that case, the GICv3 trap handling code is
skipped using a goto.  This avoids pointlessly evaluating the
static branch check for the GICv3 case, even though we can't have
vgic_v2_cpuif_trap and vgic_v3_cpuif_trap true simultaneously
unless we have a GICv3 and GICv2 on the host: that sounds stupid,
but I haven't satisfied myself that it can't happen.

No functional change.

Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Acked-by: default avatarChristoffer Dall <christoffer.dall@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent ba4f4cb0

arch/arm64/kvm/hyp/switch.c

+8 −4
Original line number Diff line number Diff line
@@ -387,11 +387,13 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) 
	 * same PC once the SError has been injected, and replay the

	 * trapping instruction.

	 */

	if (*exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu))

	if (*exit_code != ARM_EXCEPTION_TRAP)

		goto exit;



	if (!__populate_fault_info(vcpu))

		return true;



	if (static_branch_unlikely(&vgic_v2_cpuif_trap) &&

	    *exit_code == ARM_EXCEPTION_TRAP) {

	if (static_branch_unlikely(&vgic_v2_cpuif_trap)) {

		bool valid;



		valid = kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_DABT_LOW &&
@@ -417,11 +419,12 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) 
					*vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS;

				*exit_code = ARM_EXCEPTION_EL1_SERROR;

			}



			goto exit;

		}

	}



	if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&

	    *exit_code == ARM_EXCEPTION_TRAP &&

	    (kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 ||

	     kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_CP15_32)) {

		int ret = __vgic_v3_perform_cpuif_access(vcpu);
@@ -430,6 +433,7 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) 
			return true;

	}



exit:

	/* Return to the host kernel and handle the exit */

	return false;

}