[PATCH v3 13/13] KVM: arm64: Force guest's HCR_EL2.E2H RES1 when NV1 is not implemented

From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: [PATCH v3 13/13] KVM: arm64: Force guest's HCR_EL2.E2H RES1 when NV1 is not implemented
Date: Mon, 27 Nov 2023 11:45:59 +0000	[thread overview]
Message-ID: <20231127114559.990314-14-maz@kernel.org> (raw)
In-Reply-To: <20231127114559.990314-1-maz@kernel.org>

If NV1 isn't supported on a system, make sure we always evaluate
the guest's HCR_EL2.E2H as RES1, irrespective of what the guest
may have written there.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/kvm_emulate.h |  3 ++-
 arch/arm64/kvm/sys_regs.c            | 12 +++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 78a550537b67..7b10a44189d0 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -213,7 +213,8 @@ static inline bool vcpu_is_el2(const struct kvm_vcpu *vcpu)
 
 static inline bool __vcpu_el2_e2h_is_set(const struct kvm_cpu_context *ctxt)
 {
-	return ctxt_sys_reg(ctxt, HCR_EL2) & HCR_E2H;
+	return (cpus_have_final_cap(ARM64_HCR_NV1_RES0) ||
+		(ctxt_sys_reg(ctxt, HCR_EL2) & HCR_E2H));
 }
 
 static inline bool vcpu_el2_e2h_is_set(const struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index ff2e66f0bda1..9e1e3da2ed4a 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2022,6 +2022,16 @@ static bool access_spsr(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static u64 reset_hcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
+{
+	u64 val = r->val;
+
+	if (cpus_have_final_cap(ARM64_HCR_NV1_RES0))
+		val |= HCR_E2H;
+
+	return __vcpu_sys_reg(vcpu, r->reg) = val;
+}
+
 /*
  * Architected system registers.
  * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
@@ -2513,7 +2523,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	EL2_REG(VMPIDR_EL2, access_rw, reset_unknown, 0),
 	EL2_REG(SCTLR_EL2, access_rw, reset_val, SCTLR_EL2_RES1),
 	EL2_REG(ACTLR_EL2, access_rw, reset_val, 0),
-	EL2_REG(HCR_EL2, access_rw, reset_val, 0),
+	EL2_REG(HCR_EL2, access_rw, reset_hcr, 0),
 	EL2_REG(MDCR_EL2, access_rw, reset_val, 0),
 	EL2_REG(CPTR_EL2, access_rw, reset_val, CPTR_NVHE_EL2_RES1),
 	EL2_REG(HSTR_EL2, access_rw, reset_val, 0),
-- 
2.39.2

