linux-kernel - [PATCH 36/52] arm64: KVM: Make PSCI

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Message-Id: <1519633227-29832-37-git-send-email-alex.shi@linaro.org>
Date:   Mon, 26 Feb 2018 16:20:10 +0800
From:   Alex Shi <alex.shi@...aro.org>
To:     Marc Zyngier <marc.zyngier@....com>,
        Will Deacon <will.deacon@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        stable@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        kvm@...r.kernel.org (open list:KERNEL VIRTUAL MACHINE (KVM)),
        linux-arm-kernel@...ts.infradead.org (moderated list:KERNEL VIRTUAL
        MACHINE FOR ARM64 (KVM/arm64)),
        kvmarm@...ts.cs.columbia.edu (open list:KERNEL VIRTUAL MACHINE FOR
        ARM64 (KVM/arm64)), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 36/52] arm64: KVM: Make PSCI_VERSION a fast path

From: Marc Zyngier <marc.zyngier@....com>

commit 90348689d500 upstream.

For those CPUs that require PSCI to perform a BP invalidation,
going all the way to the PSCI code for not much is a waste of
precious cycles. Let's terminate that call as early as possible.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Alex Shi <alex.shi@...aro.org>
---
 arch/arm64/kvm/hyp/switch.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index cf6d962..3eab6ac 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -17,6 +17,7 @@
 
 #include <linux/types.h>
 #include <linux/jump_label.h>
+#include <uapi/linux/psci.h>
 
 #include <asm/kvm_asm.h>
 #include <asm/kvm_emulate.h>
@@ -308,6 +309,18 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 	if (exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu))
 		goto again;
 
+	if (exit_code == ARM_EXCEPTION_TRAP &&
+	    (kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_HVC64 ||
+	     kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_HVC32) &&
+	    vcpu_get_reg(vcpu, 0) == PSCI_0_2_FN_PSCI_VERSION) {
+		u64 val = PSCI_RET_NOT_SUPPORTED;
+		if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
+			val = 2;
+
+		vcpu_set_reg(vcpu, 0, val);
+		goto again;
+	}
+
 	if (static_branch_unlikely(&vgic_v2_cpuif_trap) &&
 	    exit_code == ARM_EXCEPTION_TRAP) {
 		bool valid;
-- 
2.7.4