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From: Andres Freund <andres@anarazel.de>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	Eric Dumazet <edumazet@google.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	c@redhat.com, Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	"David S. Miller" <davem@davemloft.net>,
	Guenter Roeck <linux@roeck-us.net>
Subject: Re: upstream kernel crashes
Date: Mon, 15 Aug 2022 14:10:35 -0700	[thread overview]
Message-ID: <20220815211035.r2ojxkilwsbxyewu@awork3.anarazel.de> (raw)
In-Reply-To: <20220815210437.saptyw6clr7datun@awork3.anarazel.de>

Hi,

On 2022-08-15 14:04:37 -0700, Andres Freund wrote:
> Booting with the equivalent change, atop 5.19, in the legacy setup_vq()
> reliably causes boot to hang:

I don't know much virtio, so take this with a rock of salt:

Legacy setup_vq() doesn't tell the host about the queue size. The modern one
does:
	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
but the legacy one doesn't.

I assume this means the host will assume the queue is of the size suggested by
vp_legacy_get_queue_size(). If the host continues to write into the space
after the "assumed end" of the queue, but the guest puts other stuff in that
space, well, I'd expect fun roughly like the stuff we've been seeing in this
and related threads.

Greetings,

Andres Freund
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

WARNING: multiple messages have this Message-ID (diff)
From: Andres Freund <andres@anarazel.de>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
	Jason Wang <jasowang@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Guenter Roeck <linux@roeck-us.net>,
	linux-kernel@vger.kernel.org,
	Greg KH <gregkh@linuxfoundation.org>,
	c@redhat.com
Subject: Re: upstream kernel crashes
Date: Mon, 15 Aug 2022 14:10:35 -0700	[thread overview]
Message-ID: <20220815211035.r2ojxkilwsbxyewu@awork3.anarazel.de> (raw)
In-Reply-To: <20220815210437.saptyw6clr7datun@awork3.anarazel.de>

Hi,

On 2022-08-15 14:04:37 -0700, Andres Freund wrote:
> Booting with the equivalent change, atop 5.19, in the legacy setup_vq()
> reliably causes boot to hang:

I don't know much virtio, so take this with a rock of salt:

Legacy setup_vq() doesn't tell the host about the queue size. The modern one
does:
	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
but the legacy one doesn't.

I assume this means the host will assume the queue is of the size suggested by
vp_legacy_get_queue_size(). If the host continues to write into the space
after the "assumed end" of the queue, but the guest puts other stuff in that
space, well, I'd expect fun roughly like the stuff we've been seeing in this
and related threads.

Greetings,

Andres Freund

  reply	other threads:[~2022-08-15 21:10 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-14 21:26 upstream kernel crashes Guenter Roeck
2022-08-14 21:40 ` Linus Torvalds
2022-08-14 22:37   ` Andres Freund
2022-08-14 22:47     ` Linus Torvalds
2022-08-15  1:04       ` Jens Axboe
2022-08-15  1:36         ` Andres Freund
2022-08-15  3:18           ` Linus Torvalds
2022-08-15  7:11             ` Andres Freund
2022-08-15  7:29               ` Michael S. Tsirkin
2022-08-15  7:46                 ` Andres Freund
2022-08-15  7:53                   ` Michael S. Tsirkin
2022-08-15  8:02                   ` Michael S. Tsirkin
2022-08-15  8:02                     ` Michael S. Tsirkin
2022-08-15  7:51               ` Michael S. Tsirkin
2022-08-15  8:15                 ` Andres Freund
2022-08-15  8:28                   ` Michael S. Tsirkin
2022-08-15  8:34                     ` Andres Freund
2022-08-15 15:40                       ` Michael S. Tsirkin
2022-08-15 15:40                         ` Michael S. Tsirkin
2022-08-15 16:45                         ` Andres Freund
2022-08-15 16:45                           ` Andres Freund
2022-08-15 16:50                           ` Michael S. Tsirkin
2022-08-15 16:50                             ` Michael S. Tsirkin
2022-08-15 17:46                             ` Andres Freund
2022-08-15 17:46                               ` Andres Freund
2022-08-15 20:21                               ` Michael S. Tsirkin
2022-08-15 20:21                                 ` Michael S. Tsirkin
2022-08-15 20:53                                 ` Andres Freund
2022-08-15 20:53                                   ` Andres Freund
2022-08-15 21:04                                   ` Andres Freund
2022-08-15 21:04                                     ` Andres Freund
2022-08-15 21:10                                     ` Andres Freund [this message]
2022-08-15 21:10                                       ` Andres Freund
2022-08-15 21:32                                   ` Michael S. Tsirkin
2022-08-15 21:32                                     ` Michael S. Tsirkin
2022-08-16  2:45                                     ` Xuan Zhuo
2022-08-16  2:45                                       ` Xuan Zhuo
2022-08-17  6:13                                     ` Dmitry Vyukov
2022-08-17  6:13                                       ` Dmitry Vyukov via Virtualization
2022-08-17  6:36                                       ` Xuan Zhuo
2022-08-17  6:36                                         ` Xuan Zhuo
2022-08-17 10:53                                         ` Michael S. Tsirkin
2022-08-17 10:53                                           ` Michael S. Tsirkin
2022-08-17 15:58                                         ` Linus Torvalds
2022-08-17 15:58                                           ` Linus Torvalds
2022-08-18  1:55                                           ` Xuan Zhuo
2022-08-18  1:55                                             ` Xuan Zhuo
2022-08-15 20:45                             ` Guenter Roeck
2022-08-15 20:45                               ` Guenter Roeck
2022-08-15  6:36           ` Michael S. Tsirkin
2022-08-15  7:17             ` Andres Freund
2022-08-15  7:43               ` Michael S. Tsirkin
2022-08-15  1:17       ` Guenter Roeck
2022-08-15  1:29         ` Jens Axboe
2022-08-15  9:43 ` Michael S. Tsirkin
2022-08-15 15:49   ` Guenter Roeck
2022-08-15 16:01     ` Michael S. Tsirkin
2022-08-15 18:22       ` Guenter Roeck
2022-08-15 18:37         ` Linus Torvalds
2022-08-15 20:38           ` Guenter Roeck
2022-08-17 17:12 ` Linus Torvalds
2022-08-18  1:08   ` Andres Freund

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