Re: [PATCH v2 12/21] target/arm: Read debug-related ID registers from KVM

[Richard Henderson]

On 2/14/20 9:51 AM, Peter Maydell wrote:
> +        /*
> +         * DBGDIDR is a bit complicated because the kernel doesn't
> +         * provide an accessor for it in 64-bit mode, which is what this
> +         * scratch VM is in, and there's no architected "64-bit sysreg
> +         * which reads the same as the 32-bit register" the way there is
> +         * for other ID registers. Instead we synthesize a value from the
> +         * AArch64 ID_AA64DFR0, the same way the kernel code in
> +         * arch/arm64/kvm/sys_regs.c:trap_dbgidr() does.
> +         * We only do this if the CPU supports AArch32 at EL1.
> +         */
> +        if (FIELD_EX32(ahcf->isar.id_aa64pfr0, ID_AA64PFR0, EL1) >= 2) {
> +            int wrps = FIELD_EX64(ahcf->isar.id_aa64dfr0, ID_AA64DFR0, WRPS);
> +            int brps = FIELD_EX64(ahcf->isar.id_aa64dfr0, ID_AA64DFR0, BRPS);
> +            int ctx_cmps =
> +                FIELD_EX64(ahcf->isar.id_aa64dfr0, ID_AA64DFR0, CTX_CMPS);
> +            int version = 6; /* ARMv8 debug architecture */
> +            bool has_el3 =
> +                !!FIELD_EX32(ahcf->isar.id_aa64pfr0, ID_AA64PFR0, EL3);
> +            uint32_t dbgdidr = 0;
> +
> +            dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, WRPS, wrps);
> +            dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, BRPS, brps);
> +            dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, CTX_CMPS, ctx_cmps);
> +            dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, VERSION, version);
> +            dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, NSUHD_IMP, has_el3);
> +            dbgdidr = FIELD_DP32(dbgdidr, DBGDIDR, SE_IMP, has_el3);
> +            dbgdidr |= (1 << 16); /* RES1 bit */

I see the RES1 bit as 15.

Otherwise,
Reviewed-by: Richard Henderson <address@hidden>


r~