Michael S. Tsirkin cbb726e6c6 virtio: acknowledge all features before access ... commit 4fa59ede95 upstream. The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f91 ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang <jasowang@redhat.com> Cc: stable@vger.kernel.org Fixes: 404123c2db ("virtio: allow drivers to validate features") Fixes: 2f9a174f91 ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" <pasic@linux.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2022-03-16 14:23:43 +01:00
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Kconfig	virtio-pci: introduce modern device module	2021-02-23 07:52:58 -05:00
Makefile	virtio-pci: introduce modern device module	2021-02-23 07:52:58 -05:00
virtio.c	virtio: acknowledge all features before access	2022-03-16 14:23:43 +01:00
virtio_balloon.c	virtio-balloon: Use virtio_find_vqs() helper	2021-09-06 07:20:56 -04:00
virtio_dma_buf.c	virtio: fix build for configs without dma-bufs	2020-08-19 06:43:28 +02:00
virtio_input.c	virtio-input: add multi-touch support	2021-02-23 07:52:59 -05:00
virtio_mem.c	virtio/virtio_mem: handle a possible NULL as a memcpy parameter	2022-01-27 11:02:59 +01:00
virtio_mmio.c	virtio-mmio: Use to_virtio_mmio_device() to simply code	2021-03-14 04:37:35 -04:00
virtio_pci_common.c	virtio_pci: Support surprise removal of virtio pci device	2021-08-10 11:50:55 -04:00
virtio_pci_common.h	virtio-pci: introduce modern device module	2021-02-23 07:52:58 -05:00
virtio_pci_legacy.c
virtio_pci_modern.c	virtio_pci_modern: __force cast the notify mapping	2021-05-04 04:19:58 -04:00
virtio_pci_modern_dev.c	virtio-pci library: introduce vp_modern_get_driver_features()	2021-07-08 07:49:01 -04:00
virtio_ring.c	virtio_ring: mark ring unused on error	2022-01-27 11:05:35 +01:00
virtio_vdpa.c	virtio_vdpa: reject invalid vq indices	2021-08-11 06:44:23 -04:00