Messages in this thread | | | Date | Thu, 27 Aug 2015 13:56:46 +0200 | From | Eric Auger <> | Subject | Re: [PATCH v4 0/4] VFIO platform reset |
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Hi Marc,
I tested the series on Calxeda Midway with VFIO use case. Also reviewed it again without finding anything new.
Tested-by: Eric Auger <eric.auger@linaro.org> Reviewed-by: Eric Auger <eric.auger@linaro.org>
Best Regards
Eric
On 06/15/2015 11:09 AM, Eric Auger wrote: > In situations where the userspace driver is stopped abnormally and the > VFIO platform device is released, the assigned HW device currently is > left running. As a consequence the HW device might continue issuing IRQs > and performing DMA accesses. > > On release, no physical IRQ handler is setup anymore. Also the DMA buffers > are unmapped leading to IOMMU aborts. So there is no serious consequence. > > However when assigning that HW device again to another userspace driver, > this latter might face some unexpected IRQs and DMA accesses, which are > the result of the previous assignment. > > In virtualization use-case, a VM newly granted with that HW device may be > impacted by the assignment of that device to a previous VM: > - IRQs may be injected very early when booting the new guest, even before > the guest driver has initialized leading to possible driver state > inconsistency. > - DMA accesses may hit the newly mapped VM address space at addresses that > may jeopardize the integrity of the newly installed VM. > > Obviously the criticity depends on the assigned HW device. > > As opposed to PCI, there is no standard mechanism to reset the platform > device. > > This series proposes to implement device specific reset functions in > separate in-kernel vfio reset modules. The vfio-platform driver holds > a whitelist of implemented triplets (compat string, module name, > reset function name). When the vfio-platform driver is probed it identifies > the fellow reset module/function matching the compat string of the > device, if any, and forces the load of this reset module. > > A first reset module is provided: the vfio-platform-calxedaxgmac > module which implements a basic reset for the Calxeda xgmac. > > The series can be found at > https://git.linaro.org/people/eric.auger/linux.git/shortlog/refs/heads/v4.1-rc8-reset-v4 > > History: > v3 -> v4: > - fix the commit message of "VFIO: platform: add reset struct and lookup table" > > v2 -> v3: > - remove void module_init/exit functions in calxeda reset module > - remove enum vfio_platform_reset_type > - for reset lookup, use ARRAY_SIZE > - in reset put use symbol_put_addr > > v1 -> v2: > - much simplified compared to v1 although principle of external modules is > kept: removed mechanism of dynamic registration of reset functions > - list is replaced by whitelist lookup table > - name of the reset function also stored in the lookup table > - autoload of reset modules > > RFC -> PATCH v1: > - solution now based on a lookup list instead of specialized driver > > > Eric Auger (4): > VFIO: platform: add reset struct and lookup table > VFIO: platform: add reset callback > VFIO: platform: populate the reset function on probe > VFIO: platform: Calxeda xgmac reset module > > drivers/vfio/platform/Kconfig | 2 + > drivers/vfio/platform/Makefile | 2 + > drivers/vfio/platform/reset/Kconfig | 7 ++ > drivers/vfio/platform/reset/Makefile | 5 ++ > .../platform/reset/vfio_platform_calxedaxgmac.c | 86 ++++++++++++++++++++++ > drivers/vfio/platform/vfio_platform_common.c | 60 ++++++++++++++- > drivers/vfio/platform/vfio_platform_private.h | 7 ++ > 7 files changed, 166 insertions(+), 3 deletions(-) > create mode 100644 drivers/vfio/platform/reset/Kconfig > create mode 100644 drivers/vfio/platform/reset/Makefile > create mode 100644 drivers/vfio/platform/reset/vfio_platform_calxedaxgmac.c >
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