Re: [Qemu-devel] [V15 3/4] hw/i386: Introduce AMD IOMMU

[Peter Xu <peterx@redhat.com>]

On Tue, Aug 02, 2016 at 11:39:06AM +0300, David Kiarie wrote:

[...]

> +/* invalidate internal caches for devid */
> +typedef struct QEMU_PACKED {
> +#ifdef HOST_WORDS_BIGENDIAN
> +    uint64_t devid;                /* device to invalidate   */
> +    uint64_t reserved_1:44;
> +    uint64_t type:4;               /* command type           */
> +#else
> +    uint64_t devid;
> +    uint64_t reserved_1:44;
> +    uint64_t type:4;
> +#endif /* __BIG_ENDIAN_BITFIELD */

Guess you forgot to reverse the order of fields in one of above block.

[...]

> +/* load adddress translation info for devid into translation cache */
> +typedef struct QEMU_PACKED {
> +#ifdef HOST_WORDS_BIGENDIAN
> +    uint64_t type:4;          /* command type       */
> +    uint64_t reserved_2:8;
> +    uint64_t pasid_19_0:20;
> +    uint64_t pfcount_7_0:8;
> +    uint64_t reserved_1:8;
> +    uint64_t devid;           /* related devid      */
> +#else
> +    uint64_t devid;
> +    uint64_t reserved_1:8;
> +    uint64_t pfcount_7_0:8;
> +    uint64_t pasid_19_0:20;
> +    uint64_t reserved_2:8;
> +    uint64_t type:4;
> +#endif /* __BIG_ENDIAN_BITFIELD */

For this one, "devid" looks like a 16 bits field?

[...]

> +/* issue a PCIe completion packet for devid */
> +typedef struct QEMU_PACKED {
> +#ifdef HOST_WORDS_BIGENDIAN
> +    uint32_t devid;               /* related devid      */
> +    uint32_t reserved_1;
> +#else
> +    uint32_t reserved_1;
> +    uint32_t devid;
> +#endif /* __BIG_ENDIAN_BITFIELD */

Here I am not sure we need this "#ifdef".

[...]

> +/* external write */
> +static void amdvi_writew(AMDVIState *s, hwaddr addr, uint16_t val)
> +{
> +    uint16_t romask = lduw_le_p(&s->romask[addr]);
> +    uint16_t w1cmask = lduw_le_p(&s->w1cmask[addr]);
> +    uint16_t oldval = lduw_le_p(&s->mmior[addr]);
> +    stw_le_p(&s->mmior[addr], (val & ~(val & w1cmask)) | (romask & oldval));

I think the above is problematic, e.g., what if we write 1 to one of
the romask while it's 0 originally? In that case, the RO bit will be
written to 1.

Maybe we need:

  stw_le_p(&s->mmior[addr], ((oldval & romask) | (val & ~romask)) & \
                            (val & w1cmask));

Same question to the below two functions.

> +}
> +
> +static void amdvi_writel(AMDVIState *s, hwaddr addr, uint32_t val)
> +{
> +    uint32_t romask = ldl_le_p(&s->romask[addr]);
> +    uint32_t w1cmask = ldl_le_p(&s->w1cmask[addr]);
> +    uint32_t oldval = ldl_le_p(&s->mmior[addr]);
> +    stl_le_p(&s->mmior[addr], (val & ~(val & w1cmask)) | (romask & oldval));
> +}
> +
> +static void amdvi_writeq(AMDVIState *s, hwaddr addr, uint64_t val)
> +{
> +    uint64_t romask = ldq_le_p(&s->romask[addr]);
> +    uint64_t w1cmask = ldq_le_p(&s->w1cmask[addr]);
> +    uint32_t oldval = ldq_le_p(&s->mmior[addr]);
> +    stq_le_p(&s->mmior[addr], (val & ~(val & w1cmask)) | (romask & oldval));
> +}
> +
> +/* OR a 64-bit register with a 64-bit value */
> +static bool amdvi_orq(AMDVIState *s, hwaddr addr, uint64_t val)

Nit: This function name gives me an illusion that it's a write op, not
read. IMHO it'll be better we directly use amdvi_readq() for all the
callers of this function, which is more clear to me.

> +{
> +    return amdvi_readq(s, addr) | val;
> +}
> +
> +/* OR a 64-bit register with a 64-bit value storing result in the register */
> +static void amdvi_orassignq(AMDVIState *s, hwaddr addr, uint64_t val)
> +{
> +    amdvi_writeq_raw(s, addr, amdvi_readq(s, addr) | val);
> +}
> +
> +/* AND a 64-bit register with a 64-bit value storing result in the register */
> +static void amdvi_and_assignq(AMDVIState *s, hwaddr addr, uint64_t val)

Nit: the name is not matched with above:

  amdvi_{or|and}assign[qw]

Though I would prefer:

  amdvi_assign_[qw]_{or|and}

[...]

> +static void amdvi_log_event(AMDVIState *s, uint64_t *evt)
> +{
> +    /* event logging not enabled */
> +    if (!s->evtlog_enabled || amdvi_orq(s, AMDVI_MMIO_STATUS,
> +        AMDVI_MMIO_STATUS_EVT_OVF)) {
> +        return;
> +    }
> +
> +    /* event log buffer full */
> +    if (s->evtlog_tail >= s->evtlog_len) {
> +        amdvi_orassignq(s, AMDVI_MMIO_STATUS, AMDVI_MMIO_STATUS_EVT_OVF);
> +        /* generate interrupt */
> +        amdvi_generate_msi_interrupt(s);
> +        return;
> +    }
> +
> +    if (dma_memory_write(&address_space_memory, s->evtlog_len + s->evtlog_tail,
> +        &evt, AMDVI_EVENT_LEN)) {

Check with MEMTX_OK?

[...]

> +/*
> + * AMDVi event structure
> + *    0:15   -> DeviceID
> + *    55:63  -> event type + miscellaneous info
> + *    64:127 -> related address
> + */
> +static void amdvi_encode_event(uint64_t *evt, uint16_t devid, uint64_t addr,
> +                               uint16_t info)
> +{
> +    amdvi_setevent_bits(evt, devid, 0, 16);
> +    amdvi_setevent_bits(evt, info, 55, 8);
> +    amdvi_setevent_bits(evt, addr, 63, 64);
                                      ^^
                                should here be 64?

Also, I am not sure whether we need this amdvi_setevent_bits() if it's
only used in this function. Though not a big problem for me.

> +}
> +/* log an error encountered page-walking

"during page-walking"

> + *
> + * @addr: virtual address in translation request
> + */
> +static void amdvi_page_fault(AMDVIState *s, uint16_t devid,
> +                             hwaddr addr, uint16_t info)
> +{
> +    uint64_t evt[4];
> +
> +    info |= AMDVI_EVENT_IOPF_I | AMDVI_EVENT_IOPF;
> +    amdvi_encode_event(evt, devid, addr, info);
> +    amdvi_log_event(s, evt);
> +    pci_word_test_and_set_mask(s->pci.dev.config + PCI_STATUS,
> +            PCI_STATUS_SIG_TARGET_ABORT);

Nit: maybe we can provide a function for setting this bit.

[...]

> +static void amdvi_update_iotlb(AMDVIState *s, uint16_t devid,
> +                               uint64_t gpa, IOMMUTLBEntry to_cache,
> +                               uint16_t domid)
> +{
> +    AMDVIIOTLBEntry *entry = g_malloc(sizeof(*entry));
> +    uint64_t *key = g_malloc(sizeof(key));
> +    uint64_t gfn = gpa >> AMDVI_PAGE_SHIFT_4K;
> +
> +    /* don't cache erroneous translations */
> +    if (to_cache.perm != IOMMU_NONE) {
> +        trace_amdvi_cache_update(domid, PCI_BUS_NUM(devid), PCI_SLOT(devid),
> +                PCI_FUNC(devid), gpa, to_cache.translated_addr);
> +
> +        if (g_hash_table_size(s->iotlb) >= AMDVI_IOTLB_MAX_SIZE) {
> +            trace_amdvi_iotlb_reset();

We'd better put this trace into amdvi_iotlb_reset().

> +            amdvi_iotlb_reset(s);
> +        }
> +
> +        entry->gfn = gfn;
> +        entry->domid = domid;
> +        entry->perms = to_cache.perm;
> +        entry->translated_addr = to_cache.translated_addr;
> +        entry->page_mask = to_cache.addr_mask;
> +        *key = gfn | ((uint64_t)(devid) << AMDVI_DEVID_SHIFT);
> +        g_hash_table_replace(s->iotlb, key, entry);
> +    }
> +}
> +
> +static void amdvi_completion_wait(AMDVIState *s, CMDCompletionWait *wait)
> +{
> +    /* pad the last 3 bits */
> +    hwaddr addr = cpu_to_le64(wait->store_addr << 3);

Is this correct? IMO it should be:

  hwaddr addr = le64_to_cpu(wait->store_addr) << 3;

> +    uint64_t data = cpu_to_le64(wait->store_data);

Maybe:

  uint64_t data = le64_to_cpu(wait->store_data);

?

> +
> +    if (wait->reserved) {
> +        amdvi_log_illegalcom_error(s, wait->type, s->cmdbuf + s->cmdbuf_head);
> +    }
> +
> +    if (wait->completion_store) {
> +        if (dma_memory_write(&address_space_memory, addr, &data,
> +            AMDVI_COMPLETION_DATA_SIZE))
> +        {

Left bracket is better moved upward to follow the coding style.

> +            trace_amdvi_completion_wait_fail(addr);
> +        }
> +    }

Thanks,

-- peterx