[PATCH v4 4/4] KVM: arm64: Enable writable for ID_AA64MMFR{0, 1, 2}_EL1

[Jing Zhang]

Enable writable from userspace for ID_AA64MMFR{0, 1, 2}_EL1.
Added a macro for defining general writable idregs.

Signed-off-by: Jing Zhang <jingzhangos at google.com>
---
 arch/arm64/kvm/sys_regs.c | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 8f3ad9c12b27..54c762c95983 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1391,9 +1391,6 @@ static u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 encoding)
 		val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon),
 				  pmuver_to_perfmon(vcpu_pmuver(vcpu)));
 		break;
-	case SYS_ID_AA64MMFR2_EL1:
-		val &= ~ID_AA64MMFR2_EL1_CCIDX_MASK;
-		break;
 	case SYS_ID_MMFR4_EL1:
 		val &= ~ARM64_FEATURE_MASK(ID_MMFR4_EL1_CCIDX);
 		break;
@@ -1663,6 +1660,18 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
 	return pmuver_update(vcpu, rd, val, perfmon_to_pmuver(perfmon), valid_pmu);
 }
 
+static u64 read_sanitised_id_aa64mmfr2_el1(struct kvm_vcpu *vcpu,
+					   const struct sys_reg_desc *rd)
+{
+	u64 val;
+	u32 id = reg_to_encoding(rd);
+
+	val = read_sanitised_ftr_reg(id);
+	val &= ~ID_AA64MMFR2_EL1_CCIDX_MASK;
+
+	return val;
+}
+
 /*
  * cpufeature ID register user accessors
  *
@@ -1898,6 +1907,16 @@ static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu,
 	.val = 0,				\
 }
 
+#define ID_SANITISED_WRITABLE(name) {		\
+	SYS_DESC(SYS_##name),			\
+	.access	= access_id_reg,		\
+	.get_user = get_id_reg,			\
+	.set_user = set_id_reg,			\
+	.visibility = id_visibility,		\
+	.reset = general_read_kvm_sanitised_reg,\
+	.val = GENMASK(63, 0),			\
+}
+
 /* sys_reg_desc initialiser for known cpufeature ID registers */
 #define AA32_ID_SANITISED(name) {		\
 	SYS_DESC(SYS_##name),			\
@@ -2113,9 +2132,14 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	ID_UNALLOCATED(6,7),
 
 	/* CRm=7 */
-	ID_SANITISED(ID_AA64MMFR0_EL1),
-	ID_SANITISED(ID_AA64MMFR1_EL1),
-	ID_SANITISED(ID_AA64MMFR2_EL1),
+	ID_SANITISED_WRITABLE(ID_AA64MMFR0_EL1),
+	ID_SANITISED_WRITABLE(ID_AA64MMFR1_EL1),
+	{ SYS_DESC(SYS_ID_AA64MMFR2_EL1),
+	  .access = access_id_reg,
+	  .get_user = get_id_reg,
+	  .set_user = set_id_reg,
+	  .reset = read_sanitised_id_aa64mmfr2_el1,
+	  .val = GENMASK(63, 0), },
 	ID_UNALLOCATED(7,3),
 	ID_UNALLOCATED(7,4),
 	ID_UNALLOCATED(7,5),
-- 
2.41.0.rc0.172.g3f132b7071-goog