Re: [PATCH v2] target/arm/hvf: seed NO_RAW ID registers from isar.idregs[] on vCPU init

[Zenghui Yu <zenghui.yu@linux.dev>]

On 6/30/26 4:52 AM, Jason Wright wrote:
> Commit 887eaa8a29 ("target/arm: implement FEAT_RNG_TRAP for RNDR/RNDRRS")
> gave ID_AA64ISAR0_EL1 a readfn so the RNDR field can reflect SCR_EL3.TRNDR
> at read time, and marked the cpreg ARM_CP_NO_RAW in the system-emulation
> path.  HVF then trips its hvf_arch_init_vcpu() assertion that no ID
> register in hvf_sreg_list[] is NO_RAW, aborting on boot on Apple Silicon:
> 
>   Assertion failed: (!(ri->type & ARM_CP_NO_RAW)),
>   function hvf_arch_init_vcpu, file hvf.c, line 1441.
> 
> Reproduce with:
> 
>   qemu-system-aarch64 -M virt,accel=hvf -cpu host \
>                       -nographic -display none -bios /dev/null
> 
> Fix it the same way ID_AA64PFR0_EL1 already is: list
> HV_SYS_REG_ID_AA64ISAR0_EL1 in the SYNC_NO_RAW_REGS block in sysreg.c.inc
> so the assert loop skips it, and seed the vCPU's copy at init time.
> 
> While here, unify how the three isar.idregs[]-backed ID registers are
> seeded.  isar.idregs[] already holds QEMU's intended value for each (the
> host caps, probed once at realize via hv_vcpu_config_get_feature_reg(),
> plus any QEMU adjustment), so there is no need to read each register back
> from the vCPU first.  Seed PFR0, ISAR0 and MMFR0 directly from
> isar.idregs[], dropping the two per-vCPU hv_vcpu_get_sys_reg() reads:
> 
>   - PFR0: take the GIC sysreg-interface bit from env->gicv3state, as the
>     id_aa64pfr0_read() readfn does.  Identical to the previous code
>     whenever a GICv3 sysreg interface is present (the configuration HVF
>     runs in practice); it differs only in that a vCPU with no GICv3 now
>     reports ID_AA64PFR0_EL1.GIC == 0 instead of inheriting the host's
>     value, which matches the field's meaning.
>   - ISAR0: no overlay is needed; HVF does not expose EL3, so
>     SCR_EL3.TRNDR is never set and the readfn is constant.
>   - MMFR0: still clamp PARANGE to the chosen IPA size, updating
>     isar.idregs[] in place because the page-table walker and the
>     ID_AA64MMFR0_EL1 cpreg resetvalue read PARANGE back from there.
> 
> Reported-by: Zenghui Yu <zenghui.yu@linux.dev>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Fixes: 887eaa8a29 ("target/arm: implement FEAT_RNG_TRAP for RNDR/RNDRRS")
> Signed-off-by: Jason Wright <wrigjl@proton.me>

Tested-by: Zenghui Yu <zenghui.yu@linux.dev>

Thank you for the fix!

Zenghui