Everything is now in place for a guest to "enjoy" FP8 support.
Expose ID_AA64PFR2_EL1 to both userspace and guests, with the
explicit restriction of only being able to clear FPMR.
All other features (MTE* at the time of writing) are hidden
and not writable.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/kvm/sys_regs.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 51627add0a72..da6d017f24a1 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1722,6 +1722,15 @@ static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
return val;
}
+static u64 read_sanitised_id_aa64pfr2_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ u64 val = read_sanitised_ftr_reg(SYS_ID_AA64PFR2_EL1);
+
+ /* We only expose FPMR */
+ return val & ID_AA64PFR2_EL1_FPMR;
+}
+
#define ID_REG_LIMIT_FIELD_ENUM(val, reg, field, limit) \
({ \
u64 __f_val = FIELD_GET(reg##_##field##_MASK, val); \
@@ -2381,7 +2390,12 @@ static const struct sys_reg_desc sys_reg_descs[] = {
ID_AA64PFR0_EL1_AdvSIMD |
ID_AA64PFR0_EL1_FP), },
ID_SANITISED(ID_AA64PFR1_EL1),
- ID_UNALLOCATED(4,2),
+ { SYS_DESC(SYS_ID_AA64PFR2_EL1),
+ .access = access_id_reg,
+ .get_user = get_id_reg,
+ .set_user = set_id_reg,
+ .reset = read_sanitised_id_aa64pfr2_el1,
+ .val = ID_AA64PFR2_EL1_FPMR, },
ID_UNALLOCATED(4,3),
ID_WRITABLE(ID_AA64ZFR0_EL1, ~ID_AA64ZFR0_EL1_RES0),
ID_HIDDEN(ID_AA64SMFR0_EL1),
--
2.39.2
