Relative to virtio-0.9.5, virtio-1.0 reverses the order of queue discovery and feature negotiation. In virtio-1.0, feature negotiation has to complete first, and the device can also reject a self-inconsistent feature request through the new VSTAT_FEATURES_OK status bit. (For example if the driver requests a higher level feature but clears a prerequisite feature.)
Furthermore, we retain the VIRTIO_F_VERSION_1 feature bit if the VIRTIO_DEVICE_PROTOCOL provider has high enough revision. Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Jordan Justen <jordan.l.jus...@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <ler...@redhat.com> --- OvmfPkg/VirtioRngDxe/VirtioRng.c | 27 +++++++++++++++----- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/OvmfPkg/VirtioRngDxe/VirtioRng.c b/OvmfPkg/VirtioRngDxe/VirtioRng.c index d916534aac63..1a186d04082a 100644 --- a/OvmfPkg/VirtioRngDxe/VirtioRng.c +++ b/OvmfPkg/VirtioRngDxe/VirtioRng.c @@ -238,14 +238,27 @@ VirtioRngInit ( // step 4a -- retrieve and validate features // Status = Dev->VirtIo->GetDeviceFeatures (Dev->VirtIo, &Features); if (EFI_ERROR (Status)) { goto Failed; } + Features &= VIRTIO_F_VERSION_1; + + // + // In virtio-1.0, feature negotiation is expected to complete before queue + // discovery, and the device can also reject the selected set of features. + // + if (Dev->VirtIo->Revision >= VIRTIO_SPEC_REVISION (1, 0, 0)) { + Status = Virtio10WriteFeatures (Dev->VirtIo, Features, &NextDevStat); + if (EFI_ERROR (Status)) { + goto Failed; + } + } + // // step 4b -- allocate request virtqueue, just use #0 // Status = Dev->VirtIo->SetQueueSel (Dev->VirtIo, 0); if (EFI_ERROR (Status)) { goto Failed; } @@ -286,22 +299,22 @@ VirtioRngInit ( // Status = Dev->VirtIo->SetQueueAddress (Dev->VirtIo, &Dev->Ring); if (EFI_ERROR (Status)) { goto ReleaseQueue; } // - // step 5 -- Report understood features and guest-tuneables. None are - // currently defined for VirtioRng, and no generic features are needed by - // this driver. + // step 5 -- Report understood features and guest-tuneables. // - Features &= 0; - Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features); - if (EFI_ERROR (Status)) { - goto ReleaseQueue; + if (Dev->VirtIo->Revision < VIRTIO_SPEC_REVISION (1, 0, 0)) { + Features &= ~(UINT64)VIRTIO_F_VERSION_1; + Status = Dev->VirtIo->SetGuestFeatures (Dev->VirtIo, Features); + if (EFI_ERROR (Status)) { + goto ReleaseQueue; + } } // // step 6 -- initialization complete // NextDevStat |= VSTAT_DRIVER_OK; Status = Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, NextDevStat); -- 1.8.3.1 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel