[PATCH v5 25/37] KVM: arm64: Hide S1PIE registers from userspace when disabled for guests

Marc Zyngier
2024-10-23T14:53:56Z

From: Mark Brown <broonie@kernel.org>

When the guest does not support S1PIE we should not allow any access
to the system registers it adds in order to ensure that we do not create
spurious issues with guest migration. Add a visibility operation for these
registers.

Fixes: 86f9de9db178 ("KVM: arm64: Save/restore PIE registers")
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240822-kvm-arm64-hide-pie-regs-v2-3-376624fa829c@kernel.org
[maz: simplify by using __el2_visibility(), kvm_has_s1pie() throughout]
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 3 +++
arch/arm64/kvm/at.c | 4 +--
arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 2 +-
arch/arm64/kvm/nested.c | 4 +--
arch/arm64/kvm/sys_regs.c | 31 +++++++++++++++++-----
5 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 197a7a08b3af5..9a6997827ad49 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1514,4 +1514,7 @@ void kvm_set_vm_id_reg(struct kvm *kvm, u32 reg, u64 val);
#define kvm_has_tcr2(k) \
(kvm_has_feat((k), ID_AA64MMFR3_EL1, TCRX, IMP))

+#define kvm_has_s1pie(k) \
+ (kvm_has_feat((k), ID_AA64MMFR3_EL1, S1PIE, IMP))
+
#endif /* __ARM64_KVM_HOST_H__ */
diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c
index a9f665d5ceb0b..de7109111e404 100644
--- a/arch/arm64/kvm/at.c
+++ b/arch/arm64/kvm/at.c
@@ -95,7 +95,7 @@ static enum trans_regime compute_translation_regime(struct kvm_vcpu *vcpu, u32 o

static bool s1pie_enabled(struct kvm_vcpu *vcpu, enum trans_regime regime)
{
- if (!kvm_has_feat(vcpu->kvm, ID_AA64MMFR3_EL1, S1PIE, IMP))
+ if (!kvm_has_s1pie(vcpu->kvm))
return false;

switch (regime) {
@@ -1101,7 +1101,7 @@ static u64 __kvm_at_s1e01_fast(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
write_sysreg_el1(vcpu_read_sys_reg(vcpu, MAIR_EL1), SYS_MAIR);
if (kvm_has_tcr2(vcpu->kvm)) {
write_sysreg_el1(vcpu_read_sys_reg(vcpu, TCR2_EL1), SYS_TCR2);
- if (kvm_has_feat(vcpu->kvm, ID_AA64MMFR3_EL1, S1PIE, IMP)) {
+ if (kvm_has_s1pie(vcpu->kvm)) {
write_sysreg_el1(vcpu_read_sys_reg(vcpu, PIR_EL1), SYS_PIR);
write_sysreg_el1(vcpu_read_sys_reg(vcpu, PIRE0_EL1), SYS_PIRE0);
}
diff --git a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
index c92c2c0b86aa8..a306ea70502c4 100644
--- a/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
+++ b/arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h
@@ -58,7 +58,7 @@ static inline bool ctxt_has_s1pie(struct kvm_cpu_context *ctxt)
return false;

vcpu = ctxt_to_vcpu(ctxt);
- return kvm_has_feat(kern_hyp_va(vcpu->kvm), ID_AA64MMFR3_EL1, S1PIE, IMP);
+ return kvm_has_s1pie(kern_hyp_va(vcpu->kvm));
}

static inline bool ctxt_has_tcrx(struct kvm_cpu_context *ctxt)
diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index e6d7114ef4d39..47be71279c304 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -1080,7 +1080,7 @@ int kvm_init_nv_sysregs(struct kvm *kvm)
res0 |= (HFGxTR_EL2_nSMPRI_EL1 | HFGxTR_EL2_nTPIDR2_EL0);
if (!kvm_has_feat(kvm, ID_AA64PFR1_EL1, THE, IMP))
res0 |= HFGxTR_EL2_nRCWMASK_EL1;
- if (!kvm_has_feat(kvm, ID_AA64MMFR3_EL1, S1PIE, IMP))
+ if (!kvm_has_s1pie(kvm))
res0 |= (HFGxTR_EL2_nPIRE0_EL1 | HFGxTR_EL2_nPIR_EL1);
if (!kvm_has_feat(kvm, ID_AA64MMFR3_EL1, S1POE, IMP))
res0 |= (HFGxTR_EL2_nPOR_EL0 | HFGxTR_EL2_nPOR_EL1);
@@ -1194,7 +1194,7 @@ int kvm_init_nv_sysregs(struct kvm *kvm)
res0 |= TCR2_EL2_AIE;
if (!kvm_has_feat(kvm, ID_AA64MMFR3_EL1, S1POE, IMP))
res0 |= TCR2_EL2_POE | TCR2_EL2_E0POE;
- if (!kvm_has_feat(kvm, ID_AA64MMFR3_EL1, S1PIE, IMP))
+ if (!kvm_has_s1pie(kvm))
res0 |= TCR2_EL2_PIE;
if (!kvm_has_feat(kvm, ID_AA64MMFR1_EL1, VH, IMP))
res0 |= (TCR2_EL2_E0POE | TCR2_EL2_D128 |
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 9b26514cf131f..85b465c9ec8fd 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -373,7 +373,7 @@ static bool check_s1pie_access_rw(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
- if (!kvm_has_feat(vcpu->kvm, ID_AA64MMFR3_EL1, S1PIE, IMP)) {
+ if (!kvm_has_s1pie(vcpu->kvm)) {
kvm_inject_undefined(vcpu);
return false;
}
@@ -2365,6 +2365,21 @@ static unsigned int tcr2_el2_visibility(const struct kvm_vcpu *vcpu,
return __el2_visibility(vcpu, rd, tcr2_visibility);
}

+static unsigned int s1pie_visibility(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ if (kvm_has_s1pie(vcpu->kvm))
+ return 0;
+
+ return REG_HIDDEN;
+}
+
+static unsigned int s1pie_el2_visibility(const struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ return __el2_visibility(vcpu, rd, s1pie_visibility);
+}
+
/*
* Architected system registers.
* Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
@@ -2604,8 +2619,10 @@ static const struct sys_reg_desc sys_reg_descs[] = {
{ SYS_DESC(SYS_PMMIR_EL1), trap_raz_wi },

{ SYS_DESC(SYS_MAIR_EL1), access_vm_reg, reset_unknown, MAIR_EL1 },
- { SYS_DESC(SYS_PIRE0_EL1), NULL, reset_unknown, PIRE0_EL1 },
- { SYS_DESC(SYS_PIR_EL1), NULL, reset_unknown, PIR_EL1 },
+ { SYS_DESC(SYS_PIRE0_EL1), NULL, reset_unknown, PIRE0_EL1,
+ .visibility = s1pie_visibility },
+ { SYS_DESC(SYS_PIR_EL1), NULL, reset_unknown, PIR_EL1,
+ .visibility = s1pie_visibility },
{ SYS_DESC(SYS_POR_EL1), NULL, reset_unknown, POR_EL1,
.visibility = s1poe_visibility },
{ SYS_DESC(SYS_AMAIR_EL1), access_vm_reg, reset_amair_el1, AMAIR_EL1 },
@@ -2916,8 +2933,10 @@ static const struct sys_reg_desc sys_reg_descs[] = {
EL2_REG(HPFAR_EL2, access_rw, reset_val, 0),

EL2_REG(MAIR_EL2, access_rw, reset_val, 0),
- EL2_REG(PIRE0_EL2, check_s1pie_access_rw, reset_val, 0),
- EL2_REG(PIR_EL2, check_s1pie_access_rw, reset_val, 0),
+ EL2_REG_FILTERED(PIRE0_EL2, check_s1pie_access_rw, reset_val, 0,
+ s1pie_el2_visibility),
+ EL2_REG_FILTERED(PIR_EL2, check_s1pie_access_rw, reset_val, 0,
+ s1pie_el2_visibility),
EL2_REG(AMAIR_EL2, access_rw, reset_val, 0),

EL2_REG(VBAR_EL2, access_rw, reset_val, 0),
@@ -4807,7 +4826,7 @@ void kvm_calculate_traps(struct kvm_vcpu *vcpu)
kvm->arch.fgu[HFGITR_GROUP] |= (HFGITR_EL2_ATS1E1RP |
HFGITR_EL2_ATS1E1WP);

- if (!kvm_has_feat(kvm, ID_AA64MMFR3_EL1, S1PIE, IMP))
+ if (!kvm_has_s1pie(kvm))
kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nPIRE0_EL1 |
HFGxTR_EL2_nPIR_EL1);

--
2.39.2