On 7/16/25 10:36 AM, Shameerali Kolothum Thodi wrote:
>
>> -----Original Message-----
>> From: Nicolin Chen <nicol...@nvidia.com>
>> Sent: Wednesday, July 16, 2025 12:13 AM
>> To: Shameerali Kolothum Thodi <shameerali.kolothum.th...@huawei.com>
>> Cc: qemu-...@nongnu.org; qemu-devel@nongnu.org;
>> eric.au...@redhat.com; peter.mayd...@linaro.org; j...@nvidia.com;
>> ddut...@redhat.com; berra...@redhat.com; nath...@nvidia.com;
>> mo...@nvidia.com; smost...@google.com; Linuxarm
>> <linux...@huawei.com>; Wangzhou (B) <wangzh...@hisilicon.com>;
>> jiangkunkun <jiangkun...@huawei.com>; Jonathan Cameron
>> <jonathan.came...@huawei.com>; zhangfei....@linaro.org;
>> zhenzhong.d...@intel.com; shameerkolot...@gmail.com
>> Subject: Re: [RFC PATCH v3 09/15] hw/arm/smmuv3-accel: Support nested
>> STE install/uninstall support
>>
>> On Mon, Jul 14, 2025 at 04:59:35PM +0100, Shameer Kolothum wrote:
>>> +static void
>>> +smmuv3_accel_ste_range(gpointer key, gpointer value, gpointer
>> user_data)
>>> +{
>>> + SMMUDevice *sdev = (SMMUDevice *)key;
>>> + uint32_t sid = smmu_get_sid(sdev);
>>> + SMMUSIDRange *sid_range = (SMMUSIDRange *)user_data;
>>> +
>>> + if (sid >= sid_range->start && sid <= sid_range->end) {
>>> + SMMUv3State *s = sdev->smmu;
>>> + SMMUState *bs = &s->smmu_state;
>>> +
>>> + smmuv3_accel_install_nested_ste(bs, sdev, sid);
>>> + }
>>> +}
>>> +
>>> +void
>>> +smmuv3_accel_install_nested_ste_range(SMMUState *bs,
>> SMMUSIDRange *range)
>>> +{
>>> + if (!bs->accel) {
>>> + return;
>>> + }
>>> +
>>> + g_hash_table_foreach(bs->configs, smmuv3_accel_ste_range, range);
>> This will not work correctly?
>>
>> The bs->configs is a cache that gets an entry inserted to when a
>> config is fetched via smmuv3_get_config(), which gets invoked by
>> smmuv3_notify_iova() and smmuv3_translate() only.
>>
>> But CMDQ_OP_CFGI_ALL can actually happen very early, e.g. Linux
>> driver does that in the probe() right after SMMU CMDQ is enabled,
>> at which point neither smmuv3_notify_iova nor smmuv3_translate
>> could ever get invoked, meaning that the g_hash_table is empty.
>>
>> Without the acceleration, this foreach works because vSMMU does
>> not need to do anything since the cache is indeed empty.
>>
>> But, with accel, it must call smmuv3_accel_install_nested_ste().
> Ok. The only place I can see CMDQ_OP_CFGI_ALL get invoked by Linux
Easy to say but I think we shall rather look at what the spec mandates
and not what the Linux driver does ;-)
Thanks
Eric
> kernel is during arm_smmu_device_reset() and that is to clear all.
> But I am not sure we will have any valid STEs at that time. Just curious,
> are you seeing any issues with this at the moment?
>
>> So, I think this should foreach the viommu->device_list instead.
> But agree. Using device_list is more appropriate unless we cache the
> configs during each install_netsed_ste() path.
>
> Thanks,
> Shameer
>
