From: Sebastian Ott <sebott@xxxxxxxxxx>
CTR_EL0 is currently handled as an invariant register, thus
guests will be presented with the host value of that register.
Add emulation for CTR_EL0 based on a per VM value. Userspace can
switch off DIC and IDC bits and reduce DminLine and IminLine sizes.
Naturally, ensure CTR_EL0 is trapped (HCR_EL2.TID2=1) any time that a
VM's CTR_EL0 differs from hardware.
Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxx>
Reviewed-by: Shaoqin Huang <shahuang@xxxxxxxxxx>
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 4 ++++
arch/arm64/kvm/sys_regs.c | 20 ++++++++++----------
2 files changed, 14 insertions(+), 10 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 26042875d6fc..f6de08e81d49 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -329,6 +329,8 @@ struct kvm_arch {
#define KVM_ARM_ID_REG_NUM (IDREG_IDX(sys_reg(3, 0, 0, 7, 7)) + 1)
u64 id_regs[KVM_ARM_ID_REG_NUM];
+ u64 ctr_el0;
+
/* Masks for VNCR-baked sysregs */
struct kvm_sysreg_masks *sysreg_masks;
@@ -1335,6 +1337,8 @@ static inline u64 *__vm_id_reg(struct kvm_arch *ka, u32 reg)
switch (reg) {
case sys_reg(3, 0, 0, 1, 0) ... sys_reg(3, 0, 0, 7, 7):
return &ka->id_regs[IDREG_IDX(reg)];
+ case SYS_CTR_EL0:
+ return &ka->ctr_el0;
default:
WARN_ON_ONCE(1);
return NULL;
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index a467ff4290a7..a12f3bdfb43d 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1583,6 +1583,9 @@ static bool is_feature_id_reg(u32 encoding)
*/
static inline bool is_vm_ftr_id_reg(u32 id)
{
+ if (id == SYS_CTR_EL0)
+ return true;
+
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);
@@ -1898,7 +1901,7 @@ static bool access_ctr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
if (p->is_write)
return write_to_read_only(vcpu, p, r);
- p->regval = read_sanitised_ftr_reg(SYS_CTR_EL0);
+ p->regval = kvm_read_vm_id_reg(vcpu->kvm, SYS_CTR_EL0);
return true;
}
@@ -2487,7 +2490,10 @@ static const struct sys_reg_desc sys_reg_descs[] = {
{ SYS_DESC(SYS_CCSIDR2_EL1), undef_access },
{ SYS_DESC(SYS_SMIDR_EL1), undef_access },
{ SYS_DESC(SYS_CSSELR_EL1), access_csselr, reset_unknown, CSSELR_EL1 },
- { SYS_DESC(SYS_CTR_EL0), access_ctr },
+ ID_WRITABLE(CTR_EL0, CTR_EL0_DIC_MASK |
+ CTR_EL0_IDC_MASK |
+ CTR_EL0_DminLine_MASK |
+ CTR_EL0_IminLine_MASK),
{ SYS_DESC(SYS_SVCR), undef_access },
{ PMU_SYS_REG(PMCR_EL0), .access = access_pmcr, .reset = reset_pmcr,
@@ -3725,18 +3731,11 @@ FUNCTION_INVARIANT(midr_el1)
FUNCTION_INVARIANT(revidr_el1)
FUNCTION_INVARIANT(aidr_el1)
-static u64 get_ctr_el0(struct kvm_vcpu *v, const struct sys_reg_desc *r)
-{
- ((struct sys_reg_desc *)r)->val = read_sanitised_ftr_reg(SYS_CTR_EL0);
- return ((struct sys_reg_desc *)r)->val;
-}
-
/* ->val is filled in by kvm_sys_reg_table_init() */
static struct sys_reg_desc invariant_sys_regs[] __ro_after_init = {
{ SYS_DESC(SYS_MIDR_EL1), NULL, get_midr_el1 },
{ SYS_DESC(SYS_REVIDR_EL1), NULL, get_revidr_el1 },
{ SYS_DESC(SYS_AIDR_EL1), NULL, get_aidr_el1 },
- { SYS_DESC(SYS_CTR_EL0), NULL, get_ctr_el0 },
};
static int get_invariant_sys_reg(u64 id, u64 __user *uaddr)
@@ -4086,7 +4085,8 @@ static void vcpu_set_hcr(struct kvm_vcpu *vcpu)
vcpu->arch.hcr_el2 |= HCR_FWB;
if (cpus_have_final_cap(ARM64_HAS_EVT) &&
- !cpus_have_final_cap(ARM64_MISMATCHED_CACHE_TYPE))
+ !cpus_have_final_cap(ARM64_MISMATCHED_CACHE_TYPE) &&
+ kvm_read_vm_id_reg(kvm, SYS_CTR_EL0) == read_sanitised_ftr_reg(SYS_CTR_EL0))
vcpu->arch.hcr_el2 |= HCR_TID4;
else
vcpu->arch.hcr_el2 |= HCR_TID2;
--
2.45.2.627.g7a2c4fd464-goog
