[PATCH v7 02/38] KVM: arm64: Save ID registers' sanitized value per guest
Reiji Watanabe
reijiw at google.com
Mon Apr 18 23:55:08 PDT 2022
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).
Signed-off-by: Reiji Watanabe <reijiw at google.com>
---
arch/arm64/include/asm/kvm_host.h | 11 +++++
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/sys_regs.c | 81 +++++++++++++++++++++++++------
3 files changed, 78 insertions(+), 15 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 94a27a7520f4..fc836df84748 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -150,6 +150,15 @@ struct kvm_arch {
u8 pfr0_csv2;
u8 pfr0_csv3;
+
+ /*
+ * Save ID registers for the guest in id_regs[].
+ * (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.
+ */
+#define KVM_ARM_ID_REG_MAX_NUM 56
+#define IDREG_IDX(id) (((sys_reg_CRm(id) - 1) << 3) | sys_reg_Op2(id))
+ u64 id_regs[KVM_ARM_ID_REG_MAX_NUM];
};
struct kvm_vcpu_fault_info {
@@ -775,6 +784,8 @@ 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 set_default_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 523bc934fe2f..04312f7ee0da 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -156,6 +156,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
kvm->arch.max_vcpus = kvm_arm_default_max_vcpus();
set_default_spectre(kvm);
+ set_default_id_regs(kvm);
return ret;
out_free_stage2_pgd:
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 7b45c040cc27..5b813a0b7b1c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -33,6 +33,8 @@
#include "trace.h"
+static u64 read_id_reg_with_encoding(const struct kvm_vcpu *vcpu, u32 id);
+
/*
* All of this file is extremely similar to the ARM coproc.c, but the
* types are different. My gut feeling is that it should be pretty
@@ -277,7 +279,7 @@ 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 = read_id_reg_with_encoding(vcpu, SYS_ID_AA64MMFR1_EL1);
u32 sr = reg_to_encoding(r);
if (!(val & (0xfUL << ID_AA64MMFR1_LOR_SHIFT))) {
@@ -1102,17 +1104,20 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
return true;
}
-/* 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, bool raz)
+/*
+ * 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 bool is_id_reg(u32 id)
{
- u32 id = reg_to_encoding(r);
- u64 val;
-
- if (raz)
- return 0;
+ 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);
+}
- val = read_sanitised_ftr_reg(id);
+static u64 read_id_reg_with_encoding(const struct kvm_vcpu *vcpu, u32 id)
+{
+ u64 val = vcpu->kvm->arch.id_regs[IDREG_IDX(id)];
switch (id) {
case SYS_ID_AA64PFR0_EL1:
@@ -1167,6 +1172,14 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
return val;
}
+static u64 read_id_reg(const struct kvm_vcpu *vcpu,
+ struct sys_reg_desc const *r, bool raz)
+{
+ u32 id = reg_to_encoding(r);
+
+ return raz ? 0 : read_id_reg_with_encoding(vcpu, id);
+}
+
static unsigned int id_visibility(const struct kvm_vcpu *vcpu,
const struct sys_reg_desc *r)
{
@@ -1267,9 +1280,8 @@ static int set_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
/*
* cpufeature ID register user accessors
*
- * For now, these registers are immutable for userspace, so no values
- * are stored, and for set_id_reg() we don't allow the effective value
- * to be changed.
+ * For now, these registers are immutable for userspace, so for set_id_reg()
+ * we don't allow the effective value to be changed.
*/
static int __get_id_reg(const struct kvm_vcpu *vcpu,
const struct sys_reg_desc *rd, void __user *uaddr,
@@ -1882,8 +1894,8 @@ 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 = read_id_reg_with_encoding(vcpu, SYS_ID_AA64DFR0_EL1);
+ u64 pfr = read_id_reg_with_encoding(vcpu, SYS_ID_AA64PFR0_EL1);
u32 el3 = !!cpuid_feature_extract_unsigned_field(pfr, ID_AA64PFR0_EL3_SHIFT);
p->regval = ((((dfr >> ID_AA64DFR0_WRPS_SHIFT) & 0xf) << 28) |
@@ -2895,3 +2907,42 @@ void kvm_sys_reg_table_init(void)
/* Clear all higher bits. */
cache_levels &= (1 << (i*3))-1;
}
+
+/*
+ * Set the guest's ID registers that are defined in sys_reg_descs[]
+ * with ID_SANITISED() to the host's sanitized value.
+ */
+void set_default_id_regs(struct kvm *kvm)
+{
+ int i;
+ u32 id;
+ const struct sys_reg_desc *rd;
+ u64 val;
+ struct sys_reg_params params = {
+ Op0(sys_reg_Op0(SYS_ID_PFR0_EL1)),
+ Op1(sys_reg_Op1(SYS_ID_PFR0_EL1)),
+ CRn(sys_reg_CRn(SYS_ID_PFR0_EL1)),
+ CRm(sys_reg_CRm(SYS_ID_PFR0_EL1)),
+ Op2(sys_reg_Op2(SYS_ID_PFR0_EL1)),
+ };
+
+ /*
+ * Find the first entry of the ID register (ID_PFR0_EL1) from
+ * sys_reg_descs table, and walk through only the ID register
+ * entries in the table.
+ */
+ rd = find_reg(¶ms, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
+ for (i = 0; i < KVM_ARM_ID_REG_MAX_NUM; i++, rd++) {
+ id = reg_to_encoding(rd);
+ if (WARN_ON_ONCE(!is_id_reg(id)))
+ /* Shouldn't happen */
+ continue;
+
+ if (rd->access != access_id_reg)
+ /* Hidden or reserved ID register */
+ continue;
+
+ val = read_sanitised_ftr_reg(id);
+ kvm->arch.id_regs[IDREG_IDX(id)] = val;
+ }
+}
--
2.36.0.rc0.470.gd361397f0d-goog
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