linux-kernel - [PATCH v9 03/10] arm64/kvm: expose FEAT_MTE_TAGGED

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Message-Id: <20250618084513.1761345-4-yeoreum.yun@arm.com>
Date: Wed, 18 Jun 2025 09:45:06 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: catalin.marinas@....com,
	pcc@...gle.com,
	will@...nel.org,
	broonie@...nel.org,
	anshuman.khandual@....com,
	joey.gouly@....com,
	yury.khrustalev@....com,
	maz@...nel.org,
	oliver.upton@...ux.dev,
	frederic@...nel.org,
	akpm@...ux-foundation.org,
	surenb@...gle.com
Cc: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	Yeoreum Yun <yeoreum.yun@....com>
Subject: [PATCH v9 03/10] arm64/kvm: expose FEAT_MTE_TAGGED_FAR feature to guest

expose FEAT_MTE_TAGGED_FAR feature to guest.

Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
---
 arch/arm64/kvm/sys_regs.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 76c2f0da821f..c8c92cb9da01 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1586,7 +1586,7 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 				       const struct sys_reg_desc *r)
 {
 	u32 id = reg_to_encoding(r);
-	u64 val;
+	u64 val, mask;
 
 	if (sysreg_visible_as_raz(vcpu, r))
 		return 0;
@@ -1617,8 +1617,12 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MPAM_frac);
 		break;
 	case SYS_ID_AA64PFR2_EL1:
-		/* We only expose FPMR */
-		val &= ID_AA64PFR2_EL1_FPMR;
+		mask = ID_AA64PFR2_EL1_FPMR;
+
+		if (kvm_has_mte(vcpu->kvm))
+			mask |= ID_AA64PFR2_EL1_MTEFAR;
+
+		val &= mask;
 		break;
 	case SYS_ID_AA64ISAR1_EL1:
 		if (!vcpu_has_ptrauth(vcpu))
@@ -2878,7 +2882,9 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 				       ID_AA64PFR1_EL1_MPAM_frac |
 				       ID_AA64PFR1_EL1_RAS_frac |
 				       ID_AA64PFR1_EL1_MTE)),
-	ID_WRITABLE(ID_AA64PFR2_EL1, ID_AA64PFR2_EL1_FPMR),
+	ID_WRITABLE(ID_AA64PFR2_EL1,
+		    ID_AA64PFR2_EL1_FPMR |
+		    ID_AA64PFR2_EL1_MTEFAR),
 	ID_UNALLOCATED(4,3),
 	ID_WRITABLE(ID_AA64ZFR0_EL1, ~ID_AA64ZFR0_EL1_RES0),
 	ID_HIDDEN(ID_AA64SMFR0_EL1),
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}