Re: [PATCH v2 4/4] target/arm: Add support for DC CVAP & DC CVADP ins

[Philippe Mathieu-Daudé]

Hi,

On 6/11/19 00:41, Beata Michalska wrote:
> ARMv8.2 introduced support for Data Cache Clean instructions
> to PoP (point-of-persistence) - DC CVAP and PoDP (point-of-deep-persistence)
> - DV CVADP. Both specify conceptual points in a memory system where all writes
> that are to reach them are considered persistent.
> The support provided considers both to be actually the same so there is no
> distinction between the two. If none is available (there is no backing store
> for given memory) both will result in Data Cache Clean up to the point of
> coherency. Otherwise sync for the specified range shall be performed.
>
> Signed-off-by: Beata Michalska <beata.michalska@linaro.org>
> ---
>   linux-user/elfload.c |  2 ++
>   target/arm/cpu.h     | 10 ++++++++++
>   target/arm/cpu64.c   |  1 +
>   target/arm/helper.c  | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 69 insertions(+)


> +#ifndef CONFIG_USER_ONLY
> +static void dccvap_writefn(CPUARMState *env, const ARMCPRegInfo *opaque,
> +                          uint64_t value)
> +{
> +    ARMCPU *cpu = env_archcpu(env);
> +    /* CTR_EL0 System register -> DminLine, bits [19:16] */
> +    uint64_t dline_size = 4 << ((cpu->ctr >> 16) & 0xF);
> +    uint64_t vaddr_in = (uint64_t) value;
> +    uint64_t vaddr = vaddr_in & ~(dline_size - 1);
> +    void *haddr;
> +    int mem_idx = cpu_mmu_index(env, false);
> +
> +    /* This won't be crossing page boundaries */
> +    haddr = probe_read(env, vaddr, dline_size, mem_idx, GETPC());
> +    if (haddr) {
> +
> +        ram_addr_t offset;
> +        MemoryRegion *mr;
> +
> +        /* RCU lock is already being held */
> +        mr = memory_region_from_host(haddr, &offset);
> +
> +        if (mr) {
> +            memory_region_do_writeback(mr, offset, dline_size);
> +        }
> +    }
> +}


> +#ifndef CONFIG_USER_ONLY
> +    /* Data Cache clean instructions up to PoP */
> +    if (cpu_isar_feature(aa64_dcpop, cpu)) {

Am I correct understanding this is a TCG-only feature?


> +        define_one_arm_cp_reg(cpu, dcpop_reg);
> +
> +        if (cpu_isar_feature(aa64_dcpodp, cpu)) {
> +            define_one_arm_cp_reg(cpu, dcpodp_reg);
> +        }
> +    }
> +#endif /*CONFIG_USER_ONLY*/
>   #endif
>   
>       /*