KVM: arm64: Maintain per-VM copy of implementation ID regs

Get ready to allow changes to the implementation ID registers by
tracking the VM-wide values.

Signed-off-by: Sebastian Ott <sebott@redhat.com>
Link: https://lore.kernel.org/r/20250225005401.679536-3-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 3a7ec98ef123807bf76a5dce86839acae3d577e0..b849fda62fc52344a7a0ed4077d3ad9cc9b18268 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -373,6 +373,9 @@ struct kvm_arch {
 #define KVM_ARM_ID_REG_NUM     (IDREG_IDX(sys_reg(3, 0, 0, 7, 7)) + 1)
        u64 id_regs[KVM_ARM_ID_REG_NUM];
 
+       u64 midr_el1;
+       u64 revidr_el1;
+       u64 aidr_el1;
        u64 ctr_el0;
 
        /* Masks for VNCR-backed and general EL2 sysregs */
@@ -1459,6 +1462,12 @@ static inline u64 *__vm_id_reg(struct kvm_arch *ka, u32 reg)
                return &ka->id_regs[IDREG_IDX(reg)];
        case SYS_CTR_EL0:
                return &ka->ctr_el0;
+       case SYS_MIDR_EL1:
+               return &ka->midr_el1;
+       case SYS_REVIDR_EL1:
+               return &ka->revidr_el1;
+       case SYS_AIDR_EL1:
+               return &ka->aidr_el1;
        default:
                WARN_ON_ONCE(1);
                return NULL;

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 57e945d6b715b4ff911a59e0176fb4c6d08b50de..64bbf38efed49154fd9c2445b9273ef8064e986c 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1663,15 +1663,24 @@ static bool is_feature_id_reg(u32 encoding)
  * Return true if the register's (Op0, Op1, CRn, CRm, Op2) is
  * (3, 0, 0, crm, op2), where 1<=crm<8, 0<=op2<8, which is the range of ID
  * registers KVM maintains on a per-VM basis.
+ *
+ * Additionally, the implementation ID registers and CTR_EL0 are handled as
+ * per-VM registers.
  */
 static inline bool is_vm_ftr_id_reg(u32 id)
 {
-       if (id == SYS_CTR_EL0)
+       switch (id) {
+       case SYS_CTR_EL0:
+       case SYS_MIDR_EL1:
+       case SYS_REVIDR_EL1:
+       case SYS_AIDR_EL1:
                return true;
+       default:
+               return (sys_reg_Op0(id) == 3 && sys_reg_Op1(id) == 0 &&
+                       sys_reg_CRn(id) == 0 && sys_reg_CRm(id) >= 1 &&
+                       sys_reg_CRm(id) < 8);
 
-       return (sys_reg_Op0(id) == 3 && sys_reg_Op1(id) == 0 &&
-               sys_reg_CRn(id) == 0 && sys_reg_CRm(id) >= 1 &&
-               sys_reg_CRm(id) < 8);
+       }
 }
 
 static inline bool is_vcpu_ftr_id_reg(u32 id)
@@ -2540,36 +2549,27 @@ static void init_imp_id_regs(void)
        boot_cpu_aidr_val = read_sysreg(aidr_el1);
 }
 
-static int get_imp_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
-                         u64 *val)
+static u64 reset_imp_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
 {
        switch (reg_to_encoding(r)) {
        case SYS_MIDR_EL1:
-               *val = boot_cpu_midr_val;
-               break;
+               return boot_cpu_midr_val;
        case SYS_REVIDR_EL1:
-               *val = boot_cpu_revidr_val;
-               break;
+               return boot_cpu_revidr_val;
        case SYS_AIDR_EL1:
-               *val = boot_cpu_aidr_val;
-               break;
+               return boot_cpu_aidr_val;
        default:
-               WARN_ON_ONCE(1);
-               return -EINVAL;
+               KVM_BUG_ON(1, vcpu->kvm);
+               return 0;
        }
-
-       return 0;
 }
 
 static int set_imp_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
                          u64 val)
 {
        u64 expected;
-       int ret;
 
-       ret = get_imp_id_reg(vcpu, r, &expected);
-       if (ret)
-               return ret;
+       expected = read_id_reg(vcpu, r);
 
        return (expected == val) ? 0 : -EINVAL;
 }
@@ -2577,8 +2577,9 @@ static int set_imp_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
 #define IMPLEMENTATION_ID(reg) {                       \
        SYS_DESC(SYS_##reg),                            \
        .access = access_imp_id_reg,                    \
-       .get_user = get_imp_id_reg,                     \
+       .get_user = get_id_reg,                         \
        .set_user = set_imp_id_reg,                     \
+       .reset = reset_imp_id_reg,                      \
 }
 
 /*