From: Oliver Upton <oliver.upton@xxxxxxxxx>
The debug architecture is mandatory in ARMv8, so KVM should not allow
userspace to configure a vCPU with less than that. Of course, this isn't
handled elegantly by the generic ID register plumbing, as the respective
ID register fields have a nonzero starting value.
Add an explicit check for debug versions less than v8 of the
architecture.
Signed-off-by: Oliver Upton <oliver.upton@xxxxxxxxx>
Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
---
arch/arm64/kvm/sys_regs.c | 32 +++++++++++++++++++++++++++++---
1 file changed, 29 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 6eab45ce05d9..7fcbc317f100 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1216,8 +1216,14 @@ static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp,
/* Some features have different safe value type in KVM than host features */
switch (id) {
case SYS_ID_AA64DFR0_EL1:
- if (kvm_ftr.shift == ID_AA64DFR0_EL1_PMUVer_SHIFT)
+ switch (kvm_ftr.shift) {
+ case ID_AA64DFR0_EL1_PMUVer_SHIFT:
kvm_ftr.type = FTR_LOWER_SAFE;
+ break;
+ case ID_AA64DFR0_EL1_DebugVer_SHIFT:
+ kvm_ftr.type = FTR_LOWER_SAFE;
+ break;
+ }
break;
case SYS_ID_DFR0_EL1:
if (kvm_ftr.shift == ID_DFR0_EL1_PerfMon_SHIFT)
@@ -1469,14 +1475,22 @@ static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
return val;
}
+#define ID_REG_LIMIT_FIELD_ENUM(val, reg, field, limit) \
+({ \
+ u64 __f_val = FIELD_GET(reg##_##field##_MASK, val); \
+ (val) &= ~reg##_##field##_MASK; \
+ (val) |= FIELD_PREP(reg##_##field##_MASK, \
+ min(__f_val, (u64)reg##_##field##_##limit)); \
+ (val); \
+})
+
static u64 read_sanitised_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
const struct sys_reg_desc *rd)
{
u64 val = read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1);
/* Limit debug to ARMv8.0 */
- val &= ~ID_AA64DFR0_EL1_DebugVer_MASK;
- val |= SYS_FIELD_PREP_ENUM(ID_AA64DFR0_EL1, DebugVer, IMP);
+ val = ID_REG_LIMIT_FIELD_ENUM(val, ID_AA64DFR0_EL1, DebugVer, IMP);
/*
* Only initialize the PMU version if the vCPU was configured with one.
@@ -1496,6 +1510,7 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
const struct sys_reg_desc *rd,
u64 val)
{
+ u8 debugver = SYS_FIELD_GET(ID_AA64DFR0_EL1, DebugVer, val);
u8 pmuver = SYS_FIELD_GET(ID_AA64DFR0_EL1, PMUVer, val);
/*
@@ -1515,6 +1530,13 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF)
val &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
+ /*
+ * ID_AA64DFR0_EL1.DebugVer is one of those awkward fields with a
+ * nonzero minimum safe value.
+ */
+ if (debugver < ID_AA64DFR0_EL1_DebugVer_IMP)
+ return -EINVAL;
+
return set_id_reg(vcpu, rd, val);
}
@@ -1536,6 +1558,7 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
u64 val)
{
u8 perfmon = SYS_FIELD_GET(ID_DFR0_EL1, PerfMon, val);
+ u8 copdbg = SYS_FIELD_GET(ID_DFR0_EL1, CopDbg, val);
if (perfmon == ID_DFR0_EL1_PerfMon_IMPDEF) {
val &= ~ID_DFR0_EL1_PerfMon_MASK;
@@ -1551,6 +1574,9 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
if (perfmon != 0 && perfmon < ID_DFR0_EL1_PerfMon_PMUv3)
return -EINVAL;
+ if (copdbg < ID_DFR0_EL1_CopDbg_Armv8)
+ return -EINVAL;
+
return set_id_reg(vcpu, rd, val);
}
--
2.41.0.585.gd2178a4bd4-goog
