[PATCH v10 1/5] KVM: arm64: Save ID registers' sanitized value per guest
Jing Zhang
jingzhangos at google.com
Mon May 22 15:18:31 PDT 2023
Introduce id_regs[] in kvm_arch as a storage of guest's ID registers,
and save ID registers' sanitized value in the array at KVM_CREATE_VM.
Use the saved ones when ID registers are read by the guest or
userspace (via KVM_GET_ONE_REG).
No functional change intended.
Co-developed-by: Reiji Watanabe <reijiw at google.com>
Signed-off-by: Reiji Watanabe <reijiw at google.com>
Signed-off-by: Jing Zhang <jingzhangos at google.com>
---
arch/arm64/include/asm/kvm_host.h | 20 +++++++++
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/sys_regs.c | 69 +++++++++++++++++++++++++------
arch/arm64/kvm/sys_regs.h | 7 ++++
4 files changed, 85 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 7e7e19ef6993..069606170c82 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -178,6 +178,21 @@ struct kvm_smccc_features {
unsigned long vendor_hyp_bmap;
};
+/*
+ * Emulated CPU ID registers per VM
+ * (Op0, Op1, CRn, CRm, Op2) of the ID registers to be saved in it
+ * is (3, 0, 0, crm, op2), where 1<=crm<8, 0<=op2<8.
+ *
+ * These emulated idregs are VM-wide, but accessed from the context of a vCPU.
+ * Atomic access to multiple idregs are guarded by kvm_arch.config_lock.
+ */
+#define IDREG_IDX(id) (((sys_reg_CRm(id) - 1) << 3) | sys_reg_Op2(id))
+#define IDREG(kvm, id) ((kvm)->arch.idregs.regs[IDREG_IDX(id)])
+#define KVM_ARM_ID_REG_NUM (IDREG_IDX(sys_reg(3, 0, 0, 7, 7)) + 1)
+struct kvm_idregs {
+ u64 regs[KVM_ARM_ID_REG_NUM];
+};
+
typedef unsigned int pkvm_handle_t;
struct kvm_protected_vm {
@@ -253,6 +268,9 @@ struct kvm_arch {
struct kvm_smccc_features smccc_feat;
struct maple_tree smccc_filter;
+ /* Emulated CPU ID registers */
+ struct kvm_idregs idregs;
+
/*
* For an untrusted host VM, 'pkvm.handle' is used to lookup
* the associated pKVM instance in the hypervisor.
@@ -1045,6 +1063,8 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
int kvm_vm_ioctl_set_counter_offset(struct kvm *kvm,
struct kvm_arm_counter_offset *offset);
+void kvm_arm_init_id_regs(struct kvm *kvm);
+
/* Guest/host FPSIMD coordination helpers */
int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 14391826241c..774656a0718d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -163,6 +163,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
set_default_spectre(kvm);
kvm_arm_init_hypercalls(kvm);
+ kvm_arm_init_id_regs(kvm);
/*
* Initialise the default PMUver before there is a chance to
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 71b12094d613..d2ee3a1c7f03 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -41,6 +41,7 @@
* 64bit interface.
*/
+static u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id);
static u64 sys_reg_to_index(const struct sys_reg_desc *reg);
static bool read_from_write_only(struct kvm_vcpu *vcpu,
@@ -364,7 +365,7 @@ static bool trap_loregion(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
- u64 val = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);
+ u64 val = kvm_arm_read_id_reg(vcpu, SYS_ID_AA64MMFR1_EL1);
u32 sr = reg_to_encoding(r);
if (!(val & (0xfUL << ID_AA64MMFR1_EL1_LO_SHIFT))) {
@@ -1208,16 +1209,9 @@ static u8 pmuver_to_perfmon(u8 pmuver)
}
}
-/* Read a sanitised cpufeature ID register by sys_reg_desc */
-static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r)
+static u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id)
{
- u32 id = reg_to_encoding(r);
- u64 val;
-
- if (sysreg_visible_as_raz(vcpu, r))
- return 0;
-
- val = read_sanitised_ftr_reg(id);
+ u64 val = IDREG(vcpu->kvm, id);
switch (id) {
case SYS_ID_AA64PFR0_EL1:
@@ -1280,6 +1274,26 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r
return val;
}
+/* Read a sanitised cpufeature ID register by sys_reg_desc */
+static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r)
+{
+ if (sysreg_visible_as_raz(vcpu, r))
+ return 0;
+
+ return kvm_arm_read_id_reg(vcpu, reg_to_encoding(r));
+}
+
+/*
+ * Return true if the register's (Op0, Op1, CRn, CRm, Op2) is
+ * (3, 0, 0, crm, op2), where 1<=crm<8, 0<=op2<8.
+ */
+static inline bool is_id_reg(u32 id)
+{
+ 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 unsigned int id_visibility(const struct kvm_vcpu *vcpu,
const struct sys_reg_desc *r)
{
@@ -2244,8 +2258,8 @@ static bool trap_dbgdidr(struct kvm_vcpu *vcpu,
if (p->is_write) {
return ignore_write(vcpu, p);
} else {
- u64 dfr = read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1);
- u64 pfr = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
+ u64 dfr = kvm_arm_read_id_reg(vcpu, SYS_ID_AA64DFR0_EL1);
+ u64 pfr = kvm_arm_read_id_reg(vcpu, SYS_ID_AA64PFR0_EL1);
u32 el3 = !!cpuid_feature_extract_unsigned_field(pfr, ID_AA64PFR0_EL1_EL3_SHIFT);
p->regval = ((((dfr >> ID_AA64DFR0_EL1_WRPs_SHIFT) & 0xf) << 28) |
@@ -3343,6 +3357,37 @@ int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
return write_demux_regids(uindices);
}
+/*
+ * Set the guest's ID registers with ID_SANITISED() to the host's sanitized value.
+ */
+void kvm_arm_init_id_regs(struct kvm *kvm)
+{
+ const struct sys_reg_desc *idreg;
+ struct sys_reg_params params;
+ u32 id;
+
+ /* Find the first idreg (SYS_ID_PFR0_EL1) in sys_reg_descs. */
+ id = SYS_ID_PFR0_EL1;
+ params = encoding_to_params(id);
+ idreg = find_reg(¶ms, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
+ if (WARN_ON(!idreg))
+ return;
+
+ /* Initialize all idregs */
+ while (is_id_reg(id)) {
+ /*
+ * Some hidden ID registers which are not in arm64_ftr_regs[]
+ * would cause warnings from read_sanitised_ftr_reg().
+ * Skip those ID registers to avoid the warnings.
+ */
+ if (idreg->visibility != raz_visibility)
+ IDREG(kvm, id) = read_sanitised_ftr_reg(id);
+
+ idreg++;
+ id = reg_to_encoding(idreg);
+ }
+}
+
int __init kvm_sys_reg_table_init(void)
{
bool valid = true;
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 6b11f2cc7146..eba10de2e7ae 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -27,6 +27,13 @@ struct sys_reg_params {
bool is_write;
};
+#define encoding_to_params(reg) \
+ ((struct sys_reg_params){ .Op0 = sys_reg_Op0(reg), \
+ .Op1 = sys_reg_Op1(reg), \
+ .CRn = sys_reg_CRn(reg), \
+ .CRm = sys_reg_CRm(reg), \
+ .Op2 = sys_reg_Op2(reg) })
+
#define esr_sys64_to_params(esr) \
((struct sys_reg_params){ .Op0 = ((esr) >> 20) & 3, \
.Op1 = ((esr) >> 14) & 0x7, \
--
2.40.1.698.g37aff9b760-goog
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