From: Thomas Huth <thuth@redhat.com>
To: Michael Tokarev <mjt@tls.msk.ru>,
Daniel Henrique Barboza <dbarboza@ventanamicro.com>,
qemu-devel@nongnu.org
Cc: qemu-riscv@nongnu.org, alistair.francis@wdc.com,
bmeng@tinylab.org, liwei1518@gmail.com,
zhiwei_liu@linux.alibaba.com, palmer@rivosinc.com,
lvivier@redhat.com, pbonzini@redhat.com
Subject: Re: [PATCH v2 1/6] libqos/virtio.c: init all elems in qvring_indirect_desc_setup()
Date: Fri, 1 Mar 2024 19:45:00 +0100 [thread overview]
Message-ID: <33e7f83b-329f-4cd3-9a8c-6f4436de0616@redhat.com> (raw)
In-Reply-To: <37256c80-5209-4e56-8bc2-28ee59ec42f1@tls.msk.ru>
On 01/03/2024 16.57, Michael Tokarev wrote:
> 17.02.2024 22:26, Daniel Henrique Barboza:
>
>> diff --git a/tests/qtest/libqos/virtio.c b/tests/qtest/libqos/virtio.c
>> index 410513225f..4f39124eba 100644
>> --- a/tests/qtest/libqos/virtio.c
>> +++ b/tests/qtest/libqos/virtio.c
>> @@ -280,14 +280,27 @@ QVRingIndirectDesc
>> *qvring_indirect_desc_setup(QTestState *qs, QVirtioDevice *d,
>> indirect->elem = elem;
>> indirect->desc = guest_alloc(alloc, sizeof(struct vring_desc) * elem);
>> - for (i = 0; i < elem - 1; ++i) {
>> + for (i = 0; i < elem; ++i) {
>> /* indirect->desc[i].addr */
>> qvirtio_writeq(d, qs, indirect->desc + (16 * i), 0);
>> - /* indirect->desc[i].flags */
>> - qvirtio_writew(d, qs, indirect->desc + (16 * i) + 12,
>> - VRING_DESC_F_NEXT);
>> - /* indirect->desc[i].next */
>> - qvirtio_writew(d, qs, indirect->desc + (16 * i) + 14, i + 1);
>> +
>> + /*
>> + * If it's not the last element of the ring, set
>> + * the chain (VRING_DESC_F_NEXT) flag and
>> + * desc->next. Clear the last element - there's
>> + * no guarantee that guest_alloc() will do it.
>> + */
>> + if (i != elem - 1) {
>> + /* indirect->desc[i].flags */
>> + qvirtio_writew(d, qs, indirect->desc + (16 * i) + 12,
>> + VRING_DESC_F_NEXT);
>> +
>> + /* indirect->desc[i].next */
>> + qvirtio_writew(d, qs, indirect->desc + (16 * i) + 14, i + 1);
>> + } else {
>> + qvirtio_writew(d, qs, indirect->desc + (16 * i) + 12, 0);
>> + qvirtio_writew(d, qs, indirect->desc + (16 * i) + 14, 0);
>> + }
>> }
>
> In my view it would be cleaner to add 2 extra function calls after this
> loop for the i==elem-1 case:
>
> for (i = 0; i < elem - 1; ++i) {
> /* indirect->desc[i].addr */
> qvirtio_writeq(d, qs, indirect->desc + (16 * i), 0);
> /* indirect->desc[i].flags */
> qvirtio_writew(d, qs, indirect->desc + (16 * i) + 12,
> VRING_DESC_F_NEXT);
> /* indirect->desc[i].next */
> qvirtio_writew(d, qs, indirect->desc + (16 * i) + 14, i + 1);
>
> }
>
> /* clear last element */
> qvirtio_writeq(d, qs, indirect->desc + (16 * i), 0);
> qvirtio_writew(d, qs, indirect->desc + (16 * i) + 12, 0);
> qvirtio_writew(d, qs, indirect->desc + (16 * i) + 14, 0);
>
>
> FWIW, -- it's too late to change it now I think.
Sorry, too late, since the first two patches looked like some good (and
riscv-independent) libqos fixes, I went ahead and stuck them into my pull
request today. Feel free to send a follow up patch if it bugs you too much.
Thomas
next prev parent reply other threads:[~2024-03-01 18:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-17 19:26 [PATCH v2 0/6] libqos, riscv: libqos fixes, add riscv machine Daniel Henrique Barboza
2024-02-17 19:26 ` [PATCH v2 1/6] libqos/virtio.c: init all elems in qvring_indirect_desc_setup() Daniel Henrique Barboza
2024-03-01 15:57 ` Michael Tokarev
2024-03-01 18:45 ` Thomas Huth [this message]
2024-02-17 19:26 ` [PATCH v2 2/6] libqos/virtio.c: fix 'avail_event' offset in qvring_init() Daniel Henrique Barboza
2024-02-17 19:26 ` [PATCH v2 3/6] hw/riscv/virt.c: create '/soc/pci@...' fdt node earlier Daniel Henrique Barboza
2024-02-17 19:26 ` [PATCH v2 4/6] hw/riscv/virt.c: add virtio-iommu-pci hotplug support Daniel Henrique Barboza
2024-02-17 19:26 ` [PATCH v2 5/6] hw/riscv/virt.c: make aclint compatible with 'qtest' accel Daniel Henrique Barboza
2024-02-17 19:26 ` [PATCH v2 6/6] tests/libqos: add riscv/virt machine nodes Daniel Henrique Barboza
2024-02-23 5:38 ` [PATCH v2 0/6] libqos, riscv: libqos fixes, add riscv machine Alistair Francis
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