Re: [Xen-devel] [PATCH v3 0/3] Fix xen crash when starting HVM guest due to missing io handler

[Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>]

+ Rüdiger

This patch series should help fixing the issue you are seeing.

Thanks,
Suravee

On 05/21/2016 06:42 PM, suravee.suthikulpanit@xxxxxxx wrote:
> From: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
>
> Hi All,
>
> Changes from V2:
>    * Use assert instead of sanity check before count increment in
>      the hvm_next_io_handler().
>    * Post-pone iommu_domain_init() and add proper error handling code
>      to destroy hvm in case of failure.
>    * Split out sanity check in guest_iommu_init() into a separate patch.
>
> OVERVIEW:
>
> On systems with iommu v2 enabled, the hypervisor crashes when trying
> to start up an HVM guest.
>
> Investigating shows that the guest_iommu_init() is called before the
> HVM domain is initialized. It then tries to register_mmio_handler()
> causing the hvm_next_io_handler() to increment the io_handler_count.
> However, the registration fails silently and left the I/O handler
> uninitialized.
>
> At later time, hvm_find_io_handler() is called and iterate through
> the registered handlered, but then resulting in referencing NULL
> pointers.
>
> This patch series proposes fix for this issue.
>
> Thanks,
> Suravee
>
> Suravee Suthikulpanit (3):
>    x86/hvm: Add check when register io handler
>    svm: iommu: Only call guest_iommu_init() after initialized HVM domain
>    AMD IOMMU: Check io_handler before registering mmio handler
>
>   xen/arch/x86/domain.c                     | 9 ++++++---
>   xen/arch/x86/hvm/intercept.c              | 2 ++
>   xen/drivers/passthrough/amd/iommu_guest.c | 6 ++++++
>   3 files changed, 14 insertions(+), 3 deletions(-)
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