linux-kernel - [PATCH 3/3] KVM: arm64: Expose MOPS instructions to guests

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Message-Id: <20230915124840.474888-4-kristina.martsenko@arm.com>
Date:   Fri, 15 Sep 2023 13:48:40 +0100
From:   Kristina Martsenko <kristina.martsenko@....com>
To:     kvmarm@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Cc:     Marc Zyngier <maz@...nel.org>,
        Oliver Upton <oliver.upton@...ux.dev>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Colton Lewis <coltonlewis@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] KVM: arm64: Expose MOPS instructions to guests

Expose the Armv8.8 FEAT_MOPS feature to guests in the ID register and
allow the MOPS instructions to be run in a guest. Only expose MOPS if
the whole system supports it.

Note, it is expected that guests do not use these instructions on MMIO,
similarly to other instructions where ESR_EL2.ISV==0 such as LDP/STP.

Signed-off-by: Kristina Martsenko <kristina.martsenko@....com>
---
 arch/arm64/include/asm/kvm_emulate.h           | 5 +++++
 arch/arm64/kvm/hyp/include/nvhe/fixed_config.h | 3 ++-
 arch/arm64/kvm/sys_regs.c                      | 1 -
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 64ea27e6deb1..ba46004be0e8 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -137,6 +137,11 @@ static inline void vcpu_ptrauth_disable(struct kvm_vcpu *vcpu)
 static inline void vcpu_reset_hcrx(struct kvm_vcpu *vcpu)
 {
 	vcpu->arch.hcrx_el2 = HCRX_GUEST_FLAGS;
+
+	if (cpus_have_final_cap(ARM64_HAS_MOPS)) {
+		vcpu->arch.hcrx_el2 |= HCRX_EL2_MSCEn;
+		vcpu->arch.hcrx_el2 |= HCRX_EL2_MCE2;
+	}
 }
 
 static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h b/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
index 37440e1dda93..e91922daa8ca 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/fixed_config.h
@@ -197,7 +197,8 @@
 
 #define PVM_ID_AA64ISAR2_ALLOW (\
 	ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_GPA3) | \
-	ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_APA3) \
+	ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_APA3) | \
+	ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_MOPS) \
 	)
 
 u64 pvm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index e92ec810d449..153baf2f72cb 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1338,7 +1338,6 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 				 ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_GPA3));
 		if (!cpus_have_final_cap(ARM64_HAS_WFXT))
 			val &= ~ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_WFxT);
-		val &= ~ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_MOPS);
 		break;
 	case SYS_ID_AA64MMFR2_EL1:
 		val &= ~ID_AA64MMFR2_EL1_CCIDX_MASK;
-- 
2.25.1