On Mon, 22 Jan 2024 16:28:15 +0000, Mark Brown <broonie@xxxxxxxxxx> wrote: > > FEAT_FPMR introduces a new system register FPMR which allows configuration > of floating point behaviour, currently for FP8 specific features. Allow use > of this in guests, disabling the trap while guests are running and saving > and restoring the value along with the rest of the floating point state. > Since FPMR is stored immediately after the main floating point state we > share it with the hypervisor by adjusting the size of the shared region. > > Access to FPMR is covered by both a register specific trap HCRX_EL2.EnFPM > and the overall floating point access trap so we just unconditionally > enable the FPMR specific trap and rely on the floating point access trap to > detect guest floating point usage. > > Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> > --- > arch/arm64/include/asm/kvm_arm.h | 2 +- > arch/arm64/include/asm/kvm_host.h | 3 ++- > arch/arm64/kvm/emulate-nested.c | 8 ++++++++ > arch/arm64/kvm/fpsimd.c | 2 +- > arch/arm64/kvm/hyp/include/hyp/switch.h | 7 ++++++- > arch/arm64/kvm/sys_regs.c | 11 +++++++++++ > 6 files changed, 29 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h > index 7f45ce9170bb..b2ddb6165953 100644 > --- a/arch/arm64/include/asm/kvm_arm.h > +++ b/arch/arm64/include/asm/kvm_arm.h > @@ -103,7 +103,7 @@ > #define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H) > > #define HCRX_GUEST_FLAGS \ > - (HCRX_EL2_SMPME | HCRX_EL2_TCR2En | \ > + (HCRX_EL2_SMPME | HCRX_EL2_TCR2En | HCRX_EL2_EnFPM | \ No. We don't do that anymore. This can only be enabled if the guest has it advertised via ID_AA64PFR2_EL1.FPMR. > (cpus_have_final_cap(ARM64_HAS_MOPS) ? (HCRX_EL2_MSCEn | HCRX_EL2_MCE2) : 0)) > #define HCRX_HOST_FLAGS (HCRX_EL2_MSCEn | HCRX_EL2_TCR2En | HCRX_EL2_EnFPM) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index c4fdcc94d733..99c0f8944f04 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -384,6 +384,8 @@ enum vcpu_sysreg { > APGAKEYLO_EL1, > APGAKEYHI_EL1, > > + FPMR, > + > /* Memory Tagging Extension registers */ > RGSR_EL1, /* Random Allocation Tag Seed Register */ > GCR_EL1, /* Tag Control Register */ > @@ -544,7 +546,6 @@ struct kvm_vcpu_arch { > enum fp_type fp_type; > unsigned int sve_max_vl; > u64 svcr; > - unsigned long fpmr; > > /* Stage 2 paging state used by the hardware on next switch */ > struct kvm_s2_mmu *hw_mmu; > diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c > index 431fd429932d..3af5fd0e28dc 100644 > --- a/arch/arm64/kvm/emulate-nested.c > +++ b/arch/arm64/kvm/emulate-nested.c > @@ -67,6 +67,8 @@ enum cgt_group_id { > CGT_HCR_TTLBIS, > CGT_HCR_TTLBOS, > > + CGT_HCRX_EnFPM, > + > CGT_MDCR_TPMCR, > CGT_MDCR_TPM, > CGT_MDCR_TDE, > @@ -279,6 +281,11 @@ static const struct trap_bits coarse_trap_bits[] = { > .mask = HCR_TTLBOS, > .behaviour = BEHAVE_FORWARD_ANY, > }, > + [CGT_HCRX_EnFPM] = { > + .index = HCRX_EL2, > + .mask = HCRX_EL2_EnFPM, > + .behaviour = BEHAVE_FORWARD_ANY, This is obviously incorrect. > + }, > [CGT_MDCR_TPMCR] = { > .index = MDCR_EL2, > .value = MDCR_EL2_TPMCR, > @@ -478,6 +485,7 @@ static const struct encoding_to_trap_config encoding_to_cgt[] __initconst = { > SR_TRAP(SYS_AIDR_EL1, CGT_HCR_TID1), > SR_TRAP(SYS_SMIDR_EL1, CGT_HCR_TID1), > SR_TRAP(SYS_CTR_EL0, CGT_HCR_TID2), > + SR_TRAP(SYS_FPMR, CGT_HCRX_EnFPM), > SR_TRAP(SYS_CCSIDR_EL1, CGT_HCR_TID2_TID4), > SR_TRAP(SYS_CCSIDR2_EL1, CGT_HCR_TID2_TID4), > SR_TRAP(SYS_CLIDR_EL1, CGT_HCR_TID2_TID4), > diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c > index 6cf22cd8f020..9e002489c843 100644 > --- a/arch/arm64/kvm/fpsimd.c > +++ b/arch/arm64/kvm/fpsimd.c > @@ -152,7 +152,7 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) > fp_state.sve_vl = vcpu->arch.sve_max_vl; > fp_state.sme_state = NULL; > fp_state.svcr = &vcpu->arch.svcr; > - fp_state.fpmr = &vcpu->arch.fpmr; > + fp_state.fpmr = (unsigned long *)&__vcpu_sys_reg(vcpu, FPMR); > fp_state.fp_type = &vcpu->arch.fp_type; > > if (vcpu_has_sve(vcpu)) > diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h > index 27fcdfd432b9..abf785c473d0 100644 > --- a/arch/arm64/kvm/hyp/include/hyp/switch.h > +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h > @@ -370,10 +370,15 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code) > isb(); > > /* Write out the host state if it's in the registers */ > - if (vcpu->arch.fp_state == FP_STATE_HOST_OWNED) > + if (vcpu->arch.fp_state == FP_STATE_HOST_OWNED) { > __fpsimd_save_state(&(vcpu->arch.host_uw->fpsimd_state)); > + if (cpus_have_final_cap(ARM64_HAS_FPMR)) Same thing as above: this cannot be unconditional. > + vcpu->arch.host_uw->fpmr = read_sysreg_s(SYS_FPMR); > + } > > /* Restore the guest state */ > + if (cpus_have_final_cap(ARM64_HAS_FPMR)) > + write_sysreg_s(__vcpu_sys_reg(vcpu, FPMR), SYS_FPMR); > if (sve_guest) > __hyp_sve_restore_guest(vcpu); > else > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 38503b1cd2eb..216eac44c124 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -2067,6 +2067,15 @@ static unsigned int hidden_user_visibility(const struct kvm_vcpu *vcpu, > .visibility = hidden_user_visibility, \ > } > > +static unsigned int fpmr_visibility(const struct kvm_vcpu *vcpu, > + const struct sys_reg_desc *rd) > +{ > + if (cpus_have_final_cap(ARM64_HAS_FPMR)) > + return 0; Same thing. > + > + return REG_HIDDEN; > +} > + > /* > * Since reset() callback and field val are not used for idregs, they will be > * used for specific purposes for idregs. > @@ -2463,6 +2472,8 @@ static const struct sys_reg_desc sys_reg_descs[] = { > { SYS_DESC(SYS_CSSELR_EL1), access_csselr, reset_unknown, CSSELR_EL1 }, > { SYS_DESC(SYS_CTR_EL0), access_ctr }, > { SYS_DESC(SYS_SVCR), undef_access }, > + { SYS_DESC(SYS_FPMR), access_rw, reset_unknown, FPMR, > + .visibility = fpmr_visibility }, > > { PMU_SYS_REG(PMCR_EL0), .access = access_pmcr, .reset = reset_pmcr, > .reg = PMCR_EL0, .get_user = get_pmcr, .set_user = set_pmcr }, > Thanks, M. -- Without deviation from the norm, progress is not possible.