[PATCH v6 2/6] KVM: arm64: Save ID registers' sanitized value per guest
Jing Zhang
jingzhangos at google.com
Mon Apr 3 20:53:40 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 | 21 +++++++++++++
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/id_regs.c | 49 +++++++++++++++++++++++++------
arch/arm64/kvm/sys_regs.c | 2 +-
arch/arm64/kvm/sys_regs.h | 3 +-
5 files changed, 64 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index bcd774d74f34..f0588bdce0ef 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -177,6 +177,22 @@ struct kvm_smccc_features {
unsigned long vendor_hyp_bmap;
};
+/*
+ * Emualted 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.
+ * Updating multiple id regs with dependencies needs to be guarded by
+ * kvm_arch.config_lock.
+ */
+#define KVM_ARM_ID_REG_NUM 56
+#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)]
+struct kvm_idregs {
+ u64 regs[KVM_ARM_ID_REG_NUM];
+};
+
typedef unsigned int pkvm_handle_t;
struct kvm_protected_vm {
@@ -243,6 +259,9 @@ struct kvm_arch {
/* Hypercall features firmware registers' descriptor */
struct kvm_smccc_features smccc_feat;
+ /* 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.
@@ -1008,6 +1027,8 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
long kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,
struct kvm_arm_copy_mte_tags *copy_tags);
+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 3bd732eaf087..1bf6030c8946 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -153,6 +153,7 @@ 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/id_regs.c b/arch/arm64/kvm/id_regs.c
index 96b4c43a5100..7e78957085fc 100644
--- a/arch/arm64/kvm/id_regs.c
+++ b/arch/arm64/kvm/id_regs.c
@@ -52,16 +52,9 @@ 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)
+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:
@@ -126,6 +119,14 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r
return val;
}
+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));
+}
+
/* cpufeature ID register access trap handlers */
static bool access_id_reg(struct kvm_vcpu *vcpu,
@@ -458,3 +459,33 @@ int emulate_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_params *params)
return 1;
}
+
+/*
+ * Set the guest's ID registers that are defined in id_reg_descs[]
+ * with ID_SANITISED() to the host's sanitized value.
+ */
+void kvm_arm_init_id_regs(struct kvm *kvm)
+{
+ int i;
+ u32 id;
+ u64 val;
+
+ for (i = 0; i < ARRAY_SIZE(id_reg_descs); i++) {
+ id = reg_to_encoding(&id_reg_descs[i]);
+ if (WARN_ON_ONCE(!is_id_reg(id)))
+ /* Shouldn't happen */
+ continue;
+
+ /*
+ * 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 (id_reg_descs[i].visibility == raz_visibility)
+ /* Hidden or reserved ID register */
+ continue;
+
+ val = read_sanitised_ftr_reg(id);
+ IDREG(kvm, id) = val;
+ }
+}
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index d16213adc07b..15979c2b87ab 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -364,7 +364,7 @@ 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))) {
diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h
index 7ce546a8be60..e88fd77309b2 100644
--- a/arch/arm64/kvm/sys_regs.h
+++ b/arch/arm64/kvm/sys_regs.h
@@ -237,6 +237,7 @@ bool write_to_read_only(struct kvm_vcpu *vcpu,
struct sys_reg_params *params, const struct sys_reg_desc *r);
unsigned int raz_visibility(const struct kvm_vcpu *vcpu, const struct sys_reg_desc *r);
int emulate_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_params *params);
+u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id);
#define AA32(_x) .aarch32_map = AA32_##_x
#define Op0(_x) .Op0 = _x
@@ -251,6 +252,4 @@ int emulate_id_reg(struct kvm_vcpu *vcpu, struct sys_reg_params *params);
CRn(sys_reg_CRn(reg)), CRm(sys_reg_CRm(reg)), \
Op2(sys_reg_Op2(reg))
-#define KVM_ARM_ID_REG_NUM 56
-
#endif /* __ARM64_KVM_SYS_REGS_LOCAL_H__ */
--
2.40.0.348.gf938b09366-goog
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