Messages in this thread Patch in this message | | | Subject | Re: [PATCH 2/2] iommu/virtio: Add ops->flush_iotlb_all and enable deferred flush | From | Niklas Schnelle <> | Date | Wed, 06 Sep 2023 09:55:49 +0200 |
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On Mon, 2023-09-04 at 17:33 +0100, Robin Murphy wrote: > On 2023-09-04 16:34, Jean-Philippe Brucker wrote: > > On Fri, Aug 25, 2023 at 05:21:26PM +0200, Niklas Schnelle wrote: > > > Add ops->flush_iotlb_all operation to enable virtio-iommu for the > > > dma-iommu deferred flush scheme. This results inn a significant increase > > > > in > > > > > in performance in exchange for a window in which devices can still > > > access previously IOMMU mapped memory. To get back to the prior behavior > > > iommu.strict=1 may be set on the kernel command line. > > > > Maybe add that it depends on CONFIG_IOMMU_DEFAULT_DMA_{LAZY,STRICT} as > > well, because I've seen kernel configs that enable either. > > Indeed, I'd be inclined phrase it in terms of the driver now actually > being able to honour lazy mode when requested (which happens to be the > default on x86), rather than as if it might be some > potentially-unexpected change in behaviour. > > Thanks, > Robin.
I kept running this series on a KVM guest on my private workstation (QEMU v8.0.4) and while running iperf3 on a passed-through Intel 82599 VF. I got a bunch of IOMMU events similar to the following as well as card resets in the host.
.. [ 5959.338214] vfio-pci 0000:04:10.0: AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x0037 address=0x7b657064 flags=0x0000] [ 5963.353429] ixgbe 0000:03:00.0 enp3s0: Detected Tx Unit Hang Tx Queue <0> TDH, TDT <93>, <9d> next_to_use <9d> next_to_clean <93> tx_buffer_info[next_to_clean] time_stamp <10019e800> jiffies <10019ec80> ...
I retested on v6.5 vanilla (guest & host) and still get the above errors so luckily for me it doesn't seem to be caused by the new code but I can't reproduce it without virtio-iommu. Any idea what could cause this?
> > > > Link: https://lore.kernel.org/lkml/20230802123612.GA6142@myrica/ > > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > > --- > > > drivers/iommu/virtio-iommu.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c > > > index fb73dec5b953..1b7526494490 100644 > > > --- a/drivers/iommu/virtio-iommu.c > > > +++ b/drivers/iommu/virtio-iommu.c > > > @@ -924,6 +924,15 @@ static int viommu_iotlb_sync_map(struct iommu_domain *domain, > > > return viommu_sync_req(vdomain->viommu); > > > } > > > > > > +static void viommu_flush_iotlb_all(struct iommu_domain *domain) > > > +{ > > > + struct viommu_domain *vdomain = to_viommu_domain(domain); > > > + > > > + if (!vdomain->nr_endpoints) > > > + return; > > > > As for patch 1, a NULL check in viommu_sync_req() would allow dropping > > this one > > > > Thanks, > > Jean
Right, makes sense will move the check into viommu_sync_req() and add a coment that it is there fore the cases where viommu_iotlb_sync() et al get called before the IOMMU is set up.
> > > > > + viommu_sync_req(vdomain->viommu); > > > +} > > > + > > > static void viommu_get_resv_regions(struct device *dev, struct list_head *head) > > > { > > > struct iommu_resv_region *entry, *new_entry, *msi = NULL; > > > @@ -1049,6 +1058,8 @@ static bool viommu_capable(struct device *dev, enum iommu_cap cap) > > > switch (cap) { > > > case IOMMU_CAP_CACHE_COHERENCY: > > > return true; > > > + case IOMMU_CAP_DEFERRED_FLUSH: > > > + return true; > > > default: > > > return false; > > > } > > > @@ -1069,6 +1080,7 @@ static struct iommu_ops viommu_ops = { > > > .map_pages = viommu_map_pages, > > > .unmap_pages = viommu_unmap_pages, > > > .iova_to_phys = viommu_iova_to_phys, > > > + .flush_iotlb_all = viommu_flush_iotlb_all, > > > .iotlb_sync = viommu_iotlb_sync, > > > .iotlb_sync_map = viommu_iotlb_sync_map, > > > .free = viommu_domain_free, > > > > > > -- > > > 2.39.2 > > >
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