[RFC PATCH v4 17/26] KVM: arm64: Use vcpu->arch cptr_el2 to track value of cptr_el2 for VHE

From: Reiji Watanabe <reijiw@google.com>
To: Marc Zyngier <maz@kernel.org>, kvmarm@lists.cs.columbia.edu
Cc: kvm@vger.kernel.org, Will Deacon <will@kernel.org>,
	Peter Shier <pshier@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH v4 17/26] KVM: arm64: Use vcpu->arch cptr_el2 to track value of cptr_el2 for VHE
Date: Wed,  5 Jan 2022 20:26:59 -0800	[thread overview]
Message-ID: <20220106042708.2869332-18-reijiw@google.com> (raw)
In-Reply-To: <20220106042708.2869332-1-reijiw@google.com>

Track the baseline guest value for cptr_el2 in struct kvm_vcpu_arch
for VHE.  Use this value when setting cptr_el2 for the guest.

Currently this value is unchanged, but the following patches will set
trapping bits based on features supported for the guest.

No functional change intended.

Signed-off-by: Reiji Watanabe <reijiw@google.com>
---
 arch/arm64/include/asm/kvm_arm.h | 16 ++++++++++++++++
 arch/arm64/kvm/arm.c             |  5 ++++-
 arch/arm64/kvm/hyp/vhe/switch.c  | 14 ++------------
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 01d47c5886dc..8ab6ea038721 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -288,6 +288,22 @@
 				 GENMASK(19, 14) |	\
 				 BIT(11))
 
+/*
+ * With VHE (HCR.E2H == 1), accesses to CPACR_EL1 are routed to
+ * CPTR_EL2. In general, CPACR_EL1 has the same layout as CPTR_EL2,
+ * except for some missing controls, such as TAM.
+ * In this case, CPTR_EL2.TAM has the same position with or without
+ * VHE (HCR.E2H == 1) which allows us to use here the CPTR_EL2.TAM
+ * shift value for trapping the AMU accesses.
+ */
+#define CPTR_EL2_VHE_GUEST_DEFAULT	(CPACR_EL1_TTA | CPTR_EL2_TAM)
+
+/*
+ * Bits that are copied from vcpu->arch.cptr_el2 to set cptr_el2 for
+ * guest with VHE.
+ */
+#define CPTR_EL2_VHE_GUEST_TRACKED_MASK	(CPACR_EL1_TTA | CPTR_EL2_TAM)
+
 /* Hyp Debug Configuration Register bits */
 #define MDCR_EL2_E2TB_MASK	(UL(0x3))
 #define MDCR_EL2_E2TB_SHIFT	(UL(24))
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 876f2777acf2..3700144f6271 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1136,7 +1136,10 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
 	}
 
 	vcpu_reset_hcr(vcpu);
-	vcpu->arch.cptr_el2 = CPTR_EL2_DEFAULT;
+	if (has_vhe())
+		vcpu->arch.cptr_el2 = CPTR_EL2_VHE_GUEST_DEFAULT;
+	else
+		vcpu->arch.cptr_el2 = CPTR_EL2_DEFAULT;
 
 	/*
 	 * Handle the "start in power-off" case.
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index fbb26b93c347..572b2669ae84 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -38,20 +38,10 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 	___activate_traps(vcpu);
 
 	val = read_sysreg(cpacr_el1);
-	val |= CPACR_EL1_TTA;
+	val &= ~CPTR_EL2_VHE_GUEST_TRACKED_MASK;
+	val |= (vcpu->arch.cptr_el2 & CPTR_EL2_VHE_GUEST_TRACKED_MASK);
 	val &= ~CPACR_EL1_ZEN;
 
-	/*
-	 * With VHE (HCR.E2H == 1), accesses to CPACR_EL1 are routed to
-	 * CPTR_EL2. In general, CPACR_EL1 has the same layout as CPTR_EL2,
-	 * except for some missing controls, such as TAM.
-	 * In this case, CPTR_EL2.TAM has the same position with or without
-	 * VHE (HCR.E2H == 1) which allows us to use here the CPTR_EL2.TAM
-	 * shift value for trapping the AMU accesses.
-	 */
-
-	val |= CPTR_EL2_TAM;
-
 	if (update_fp_enabled(vcpu)) {
 		if (vcpu_has_sve(vcpu))
 			val |= CPACR_EL1_ZEN;
-- 
2.34.1.448.ga2b2bfdf31-goog

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