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KVM: arm64: Fold redundant exit code checks out of fixup_guest_exit()

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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: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Dave Martin 2018-05-02 13:36:48 +01:00 committed by Marc Zyngier
parent ba4f4cb0e6
commit 7846b3119e
1 changed files with 8 additions and 4 deletions
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12
arch/arm64/kvm/hyp/switch.c
View file

@ -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;
}