[PATCH v8 40/43] arm64: RME: Provide accurate register list

[Steven Price]

From: Jean-Philippe Brucker <jean-philippe at linaro.org>

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 <jean-philippe at linaro.org>
Signed-off-by: Steven Price <steven.price at arm.com>
---
Changes since v7:
 * Reworked on upstream changes.
---
 arch/arm64/kvm/guest.c      | 19 ++++++++++++++-----
 arch/arm64/kvm/hypercalls.c |  4 ++--
 arch/arm64/kvm/sys_regs.c   | 28 ++++++++++++++++++++++------
 3 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 1288920fc73d..e9bb7647aa65 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -618,8 +618,6 @@ static const u64 timer_reg_list[] = {
 	KVM_REG_ARM_PTIMER_CVAL,
 };
 
-#define NUM_TIMER_REGS ARRAY_SIZE(timer_reg_list)
-
 static bool is_timer_reg(u64 index)
 {
 	switch (index) {
@@ -634,9 +632,14 @@ static bool is_timer_reg(u64 index)
 	return false;
 }
 
+static unsigned long num_timer_regs(struct kvm_vcpu *vcpu)
+{
+	return kvm_is_realm(vcpu->kvm) ? 0 : ARRAY_SIZE(timer_reg_list);
+}
+
 static int copy_timer_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
 {
-	for (int i = 0; i < NUM_TIMER_REGS; i++) {
+	for (int i = 0; i < num_timer_regs(vcpu); i++) {
 		if (put_user(timer_reg_list[i], uindices))
 			return -EFAULT;
 		uindices++;
@@ -674,6 +677,9 @@ static unsigned long num_sve_regs(const struct kvm_vcpu *vcpu)
 	if (!vcpu_has_sve(vcpu) || !kvm_arm_vcpu_sve_finalized(vcpu))
 		return 0;
 
+	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 */
 }
@@ -701,6 +707,9 @@ static int copy_sve_reg_indices(const struct kvm_vcpu *vcpu,
 		return -EFAULT;
 	++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);
@@ -739,7 +748,7 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
 	res += num_sve_regs(vcpu);
 	res += kvm_arm_num_sys_reg_descs(vcpu);
 	res += kvm_arm_get_fw_num_regs(vcpu);
-	res += NUM_TIMER_REGS;
+	res += num_timer_regs(vcpu);
 
 	return res;
 }
@@ -773,7 +782,7 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
 	ret = copy_timer_indices(vcpu, uindices);
 	if (ret < 0)
 		return ret;
-	uindices += NUM_TIMER_REGS;
+	uindices += num_timer_regs(vcpu);
 
 	return kvm_arm_copy_sys_reg_indices(vcpu, uindices);
 }
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 569941eeb3fe..fb2bba0c7e86 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -412,14 +412,14 @@ 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 a53a06700867..7d384016d1ba 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -4960,18 +4960,18 @@ 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 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++;
@@ -5002,11 +5002,27 @@ static bool copy_reg_to_user(const struct sys_reg_desc *reg, u64 __user **uind)
 	return true;
 }
 
+static bool kvm_realm_sys_reg_hidden_user(const struct kvm_vcpu *vcpu, u64 reg)
+{
+	if (!kvm_is_realm(vcpu->kvm))
+		return false;
+
+	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 (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.
@@ -5044,7 +5060,7 @@ 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);
 }
 
@@ -5057,7 +5073,7 @@ 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)			\
-- 
2.43.0