[PATCH v16 43/45] KVM: arm64: CCA: Provide an accurate register list
From: Steven Price <steven.price@arm.com>
Date: 2026-08-03 13:47:41
Also in:
kvm, kvmarm, linux-arm-kernel, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
From: Jean-Philippe Brucker <redacted> Userspace can set a few registers with KVM_SET_ONE_REG (9 GP registers at runtime, and 3 system registers during initialization). Update the register list returned by KVM_GET_REG_LIST. Signed-off-by: Jean-Philippe Brucker <redacted> Signed-off-by: Steven Price <steven.price@arm.com> --- Changes since v11: * Reworked due to upstream changes. Changes since v8: * Minor type changes following review. Changes since v7: * Reworked on upstream changes. --- arch/arm64/kvm/guest.c | 6 ++++++ arch/arm64/kvm/hypercalls.c | 4 ++-- arch/arm64/kvm/sys_regs.c | 27 +++++++++++++++++++++------ 3 files changed, 29 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 128fec56993a..5e495dd39e39 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c@@ -620,6 +620,9 @@ static unsigned long num_sve_regs(const struct kvm_vcpu *vcpu) if (!kvm_arm_vcpu_sve_finalized(vcpu)) return 1; /* KVM_REG_ARM64_SVE_VLS */ + if (kvm_is_realm(vcpu->kvm)) + return 1; /* KVM_REG_ARM64_SVE_VLS */ + return slices * (SVE_NUM_PREGS + SVE_NUM_ZREGS + 1 /* FFR */) + 1; /* KVM_REG_ARM64_SVE_VLS */ }
@@ -647,6 +650,9 @@ static int copy_sve_reg_indices(const struct kvm_vcpu *vcpu, if (!kvm_arm_vcpu_sve_finalized(vcpu)) return num_regs; + if (kvm_is_realm(vcpu->kvm)) + return num_regs; + for (i = 0; i < slices; i++) { for (n = 0; n < SVE_NUM_ZREGS; n++) { reg = KVM_REG_ARM64_SVE_ZREG(n, i);
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index b11b8821c9fb..82278ccb19ae 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c@@ -414,14 +414,14 @@ void kvm_arm_teardown_hypercalls(struct kvm *kvm) int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu) { - return ARRAY_SIZE(kvm_arm_fw_reg_ids); + return kvm_is_realm(vcpu->kvm) ? 0 : ARRAY_SIZE(kvm_arm_fw_reg_ids); } int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) { int i; - for (i = 0; i < ARRAY_SIZE(kvm_arm_fw_reg_ids); i++) { + for (i = 0; i < kvm_arm_get_fw_num_regs(vcpu); i++) { if (put_user(kvm_arm_fw_reg_ids[i], uindices++)) return -EFAULT; }
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index e47be8f8d259..6d805160d70e 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c@@ -5540,18 +5540,18 @@ int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); } -static unsigned int num_demux_regs(void) +static inline unsigned int num_demux_regs(struct kvm_vcpu *vcpu) { - return CSSELR_MAX; + return kvm_is_realm(vcpu->kvm) ? 0 : CSSELR_MAX; } -static int write_demux_regids(u64 __user *uindices) +static int write_demux_regids(struct kvm_vcpu *vcpu, u64 __user *uindices) { u64 val = KVM_REG_ARM64 | KVM_REG_SIZE_U32 | KVM_REG_ARM_DEMUX; unsigned int i; val |= KVM_REG_ARM_DEMUX_ID_CCSIDR; - for (i = 0; i < CSSELR_MAX; i++) { + for (i = 0; i < num_demux_regs(vcpu); i++) { if (put_user(val | i, uindices)) return -EFAULT; uindices++;
@@ -5595,11 +5595,26 @@ static bool copy_reg_to_user(const struct sys_reg_desc *reg, u64 __user **uind) return true; } +static inline bool kvm_realm_sys_reg_hidden_user(const struct kvm_vcpu *vcpu, + u64 reg) +{ + switch (reg) { + case SYS_ID_AA64DFR0_EL1: + case SYS_PMCR_EL0: + return false; + } + return true; +} + static int walk_one_sys_reg(const struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, u64 __user **uind, unsigned int *total) { + if (vcpu_is_rec(vcpu) && + kvm_realm_sys_reg_hidden_user(vcpu, reg_to_encoding(rd))) + return 0; + /* * Ignore registers we trap but don't save, * and for which no custom user accessor is provided.
@@ -5637,7 +5652,7 @@ static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind) unsigned long kvm_arm_num_sys_reg_descs(struct kvm_vcpu *vcpu) { - return num_demux_regs() + return num_demux_regs(vcpu) + walk_sys_regs(vcpu, (u64 __user *)NULL); }
@@ -5650,7 +5665,7 @@ int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) return err; uindices += err; - return write_demux_regids(uindices); + return write_demux_regids(vcpu, uindices); } #define KVM_ARM_FEATURE_ID_RANGE_INDEX(r) \
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2.43.0