[PATCH v4 08/10] KVM: arm64: Expose ID_AA64MMFR4_EL1 to guests

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>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	James Morse <james.morse@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: [PATCH v4 08/10] KVM: arm64: Expose ID_AA64MMFR4_EL1 to guests
Date: Mon, 22 Jan 2024 18:13:42 +0000	[thread overview]
Message-ID: <20240122181344.258974-9-maz@kernel.org> (raw)
In-Reply-To: <20240122181344.258974-1-maz@kernel.org>

We can now expose ID_AA64MMFR4_EL1 to guests, and let NV guests
understand that they cannot really switch HCR_EL2.E2H to 0 on
some platforms.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/nested.c   | 7 +++++++
 arch/arm64/kvm/sys_regs.c | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index ba95d044bc98..d55e809e26cb 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -133,6 +133,13 @@ static u64 limit_nv_id_reg(u32 id, u64 val)
 		val |= FIELD_PREP(NV_FTR(MMFR2, TTL), 0b0001);
 		break;
 
+	case SYS_ID_AA64MMFR4_EL1:
+		val = 0;
+		if (!cpus_have_final_cap(ARM64_HAS_HCR_NV1))
+			val |= FIELD_PREP(NV_FTR(MMFR4, E2H0),
+					  ID_AA64MMFR4_EL1_E2H0_NI_NV1);
+		break;
+
 	case SYS_ID_AA64DFR0_EL1:
 		/* Only limited support for PMU, Debug, BPs and WPs */
 		val &= (NV_FTR(DFR0, PMUVer)	|
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 88b8fbeafaa0..08a9571fa809 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -2350,7 +2350,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 					ID_AA64MMFR2_EL1_NV |
 					ID_AA64MMFR2_EL1_CCIDX)),
 	ID_SANITISED(ID_AA64MMFR3_EL1),
-	ID_UNALLOCATED(7,4),
+	ID_SANITISED(ID_AA64MMFR4_EL1),
 	ID_UNALLOCATED(7,5),
 	ID_UNALLOCATED(7,6),
 	ID_UNALLOCATED(7,7),
-- 
2.39.2


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