[PATCH v3 8/8] KVM: arm64: Expose ID_AA64PFR2_EL1 to userspace and guests
From: Marc Zyngier <maz@kernel.org>
Date: 2024-08-13 10:49:46
Also in:
kvm, kvmarm
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
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@kernel.org> --- 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),
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2.39.2