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KVM: arm64: Make ID_AA64PFR1_EL1.RAS_frac writable

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Allow userspace to write to RAS_frac, under the condition that
the host supports RASv1p1 with RAS_frac==1. Other configurations
will result in RAS_frac being exposed as 0, and therefore implicitly
not writable.

To avoid the clutter, the ID_AA64PFR1_EL1 sanitisation is moved to
its own function.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Link: https://lore.kernel.org/r/20250817202158.395078-6-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Marc Zyngier 2025-08-17 21:21:57 +01:00 • committed by Oliver Upton
parent 1fab657cb2
commit 7a765aa88e
1 changed files with 27 additions and 14 deletions
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41
arch/arm64/kvm/sys_regs.c
View file

@ -1584,6 +1584,7 @@ static u8 pmuver_to_perfmon(u8 pmuver)
}
static u64 sanitise_id_aa64pfr0_el1(const struct kvm_vcpu *vcpu, u64 val);
static u64 sanitise_id_aa64pfr1_el1(const struct kvm_vcpu *vcpu, u64 val);
static u64 sanitise_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, u64 val);
/* Read a sanitised cpufeature ID register by sys_reg_desc */
@ -1606,19 +1607,7 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
val = sanitise_id_aa64pfr0_el1(vcpu, val);
break;
case SYS_ID_AA64PFR1_EL1:
if (!kvm_has_mte(vcpu->kvm)) {
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE_frac);
}
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_SME);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RNDR_trap);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_NMI);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_GCS);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_THE);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTEX);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_PFAR);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MPAM_frac);
val = sanitise_id_aa64pfr1_el1(vcpu, val);
break;
case SYS_ID_AA64PFR2_EL1:
/* We only expose FPMR */
@ -1834,6 +1823,31 @@ static u64 sanitise_id_aa64pfr0_el1(const struct kvm_vcpu *vcpu, u64 val)
return val;
}
static u64 sanitise_id_aa64pfr1_el1(const struct kvm_vcpu *vcpu, u64 val)
{
u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1);
if (!kvm_has_mte(vcpu->kvm)) {
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE_frac);
}
if (!(cpus_have_final_cap(ARM64_HAS_RASV1P1_EXTN) &&
SYS_FIELD_GET(ID_AA64PFR0_EL1, RAS, pfr0) == ID_AA64PFR0_EL1_RAS_IMP))
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RAS_frac);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_SME);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RNDR_trap);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_NMI);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_GCS);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_THE);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTEX);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_PFAR);
val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MPAM_frac);
return val;
}
static u64 sanitise_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, u64 val)
{
val = ID_REG_LIMIT_FIELD_ENUM(val, ID_AA64DFR0_EL1, DebugVer, V8P8);
@ -2952,7 +2966,6 @@ static const struct sys_reg_desc sys_reg_descs[] = {
ID_AA64PFR1_EL1_SME |
ID_AA64PFR1_EL1_RES0 |
ID_AA64PFR1_EL1_MPAM_frac |
ID_AA64PFR1_EL1_RAS_frac |
ID_AA64PFR1_EL1_MTE)),
ID_WRITABLE(ID_AA64PFR2_EL1, ID_AA64PFR2_EL1_FPMR),
ID_UNALLOCATED(4,3),