similar to: [PATCH v2] dma-mapping: Use dma_get_mask in dma_addressing_limited

When running a guest featuring a virtio-blk-pci protected with a virtual IOMMU we hit a NULL pointer dereference. This series removes the dma_max_mapping_size() call in virtio_max_dma_size when the device does not have any dma_mask set. A check is also added to early return in dma_addressing_limited() if the dma_mask is NULL. Eric Auger (2): dma-mapping: Protect dma_addressing_limited against

Hi Christoph, On 7/22/19 6:51 PM, Eric Auger wrote: > We currently have cases where the dma_addressing_limited() gets > called with dma_mask unset. This causes a NULL pointer dereference. > > Use dma_get_mask() accessor to prevent the crash. > > Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper") > Signed-off-by: Eric Auger <eric.auger at

> static inline bool dma_addressing_limited(struct device *dev) > { > - return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) < > - dma_get_required_mask(dev); > + return WARN_ON_ONCE(!dev->dma_mask) ? false : > + min_not_zero(*dev->dma_mask, dev->bus_dma_mask) < > + dma_get_required_mask(dev); This should really use a separate if statement, but I

dma_addressing_limited() should not be called on a device with a NULL dma_mask. If this occurs let's WARN_ON_ONCE and immediately return. Existing call sites are updated separately. Fixes: b866455423e0 ("dma-mapping: add a dma_addressing_limited helper") Signed-off-by: Eric Auger <eric.auger at redhat.com> --- v1 -> v2: - add a WARN_ON_ONCE() - reword the commit message

On 22/07/2019 15:55, Eric Auger wrote: > Do not call dma_max_mapping_size for devices that have no DMA > mask set, otherwise we can hit a NULL pointer dereference. > > This occurs when a virtio-blk-pci device is protected with > a virtual IOMMU. > > Fixes: e6d6dd6c875e ("virtio: Introduce virtio_max_dma_size()") > Signed-off-by: Eric Auger <eric.auger at

On 22/07/2019 15:55, Eric Auger wrote: > Do not call dma_max_mapping_size for devices that have no DMA > mask set, otherwise we can hit a NULL pointer dereference. > > This occurs when a virtio-blk-pci device is protected with > a virtual IOMMU. > > Fixes: e6d6dd6c875e ("virtio: Introduce virtio_max_dma_size()") > Signed-off-by: Eric Auger <eric.auger at

**We would like the patches to be merged through the virtio tree. Please review, and ack merging the DMA mapping change through that tree. Thanks!** The memory of powerpc secure guests can't be accessed by the hypervisor / virtio device except for a few memory regions designated as 'shared'. At the moment, Linux uses bounce-buffering to communicate with the hypervisor, with a

On Fri, Oct 11, 2019 at 06:25:18PM -0700, Ram Pai wrote: > From: Thiago Jung Bauermann <bauerman at linux.ibm.com> > > In order to safely use the DMA API, virtio needs to know whether DMA > addresses are in fact physical addresses and for that purpose, > dma_addr_is_phys_addr() is introduced. > > cc: Benjamin Herrenschmidt <benh at kernel.crashing.org> > cc:

On Fri, Oct 11, 2019 at 06:25:18PM -0700, Ram Pai wrote: > From: Thiago Jung Bauermann <bauerman at linux.ibm.com> > > In order to safely use the DMA API, virtio needs to know whether DMA > addresses are in fact physical addresses and for that purpose, > dma_addr_is_phys_addr() is introduced. > > cc: Benjamin Herrenschmidt <benh at kernel.crashing.org> > cc:

On Mon, 2018-08-06 at 23:35 +0300, Michael S. Tsirkin wrote: > > As I said replying to Christoph, we are "leaking" into the interface > > something here that is really what's the VM is doing to itself, which > > is to stash its memory away in an inaccessible place. > > > > Cheers, > > Ben. > > I think Christoph merely objects to the

On Mon, 2018-08-06 at 23:35 +0300, Michael S. Tsirkin wrote: > > As I said replying to Christoph, we are "leaking" into the interface > > something here that is really what's the VM is doing to itself, which > > is to stash its memory away in an inaccessible place. > > > > Cheers, > > Ben. > > I think Christoph merely objects to the

On Tue, 2018-08-07 at 00:46 +0300, Michael S. Tsirkin wrote: > On Tue, Aug 07, 2018 at 07:26:35AM +1000, Benjamin Herrenschmidt wrote: > > On Mon, 2018-08-06 at 23:35 +0300, Michael S. Tsirkin wrote: > > > > As I said replying to Christoph, we are "leaking" into the interface > > > > something here that is really what's the VM is doing to itself,

On Tue, 2018-08-07 at 00:46 +0300, Michael S. Tsirkin wrote: > On Tue, Aug 07, 2018 at 07:26:35AM +1000, Benjamin Herrenschmidt wrote: > > On Mon, 2018-08-06 at 23:35 +0300, Michael S. Tsirkin wrote: > > > > As I said replying to Christoph, we are "leaking" into the interface > > > > something here that is really what's the VM is doing to itself,

On Mon, 2018-08-06 at 16:46 +0300, Michael S. Tsirkin wrote: > > > Right, we'll need some quirk to disable balloons in the guest I > > suppose. > > > > Passing something from libvirt is cumbersome because the end user may > > not even need to know about secure VMs. There are use cases where the > > security is a contract down to some special

On Mon, 2018-08-06 at 16:46 +0300, Michael S. Tsirkin wrote: > > > Right, we'll need some quirk to disable balloons in the guest I > > suppose. > > > > Passing something from libvirt is cumbersome because the end user may > > not even need to know about secure VMs. There are use cases where the > > security is a contract down to some special

On Fri, Aug 03, 2018 at 12:05:07AM -0700, Christoph Hellwig wrote: > On Thu, Aug 02, 2018 at 04:13:09PM -0500, Benjamin Herrenschmidt wrote: > > So let's differenciate the two problems of having an IOMMU (real or > > emulated) which indeeds adds overhead etc... and using the DMA API. > > > > At the moment, virtio does this all over the place: > > > >

On Fri, Aug 03, 2018 at 12:05:07AM -0700, Christoph Hellwig wrote: > On Thu, Aug 02, 2018 at 04:13:09PM -0500, Benjamin Herrenschmidt wrote: > > So let's differenciate the two problems of having an IOMMU (real or > > emulated) which indeeds adds overhead etc... and using the DMA API. > > > > At the moment, virtio does this all over the place: > > > >

On Sat, Aug 04, 2018 at 01:15:00AM -0700, Christoph Hellwig wrote: > On Fri, Aug 03, 2018 at 10:17:32PM +0300, Michael S. Tsirkin wrote: > > It seems reasonable to teach a platform to override dma-range > > for a specific device e.g. in case it knows about bugs in ACPI. > > A platform will be able override dma-range using the dev->bus_dma_mask > field starting in 4.19.

Hi, here is the next version of this patch-set. Previous versions can be found here: V1: https://lore.kernel.org/lkml/20190110134433.15672-1-joro at 8bytes.org/ V2: https://lore.kernel.org/lkml/20190115132257.6426-1-joro at 8bytes.org/ V3: https://lore.kernel.org/lkml/20190123163049.24863-1-joro at 8bytes.org/ V4: https://lore.kernel.org/lkml/20190129084342.26030-1-joro at 8bytes.org/

This patchset converts the intel iommu driver to the dma-iommu api. While converting the driver I exposed a bug in the intel i915 driver which causes a huge amount of artifacts on the screen of my laptop. You can see a picture of it here: https://github.com/pippy360/kernelPatches/blob/master/IMG_20191219_225922.jpg This issue is most likely in the i915 driver and is most likely caused by the