Re: [PATCH v2 1/4] x86/MSI-X: be more careful during teardown

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 25/03/15 16:39, Jan Beulich wrote:
> When a device gets detached from a guest, pciback will clear its
> command register, thus disabling both memory and I/O decoding. The
> disabled memory decoding, however, has an effect on the MSI-X table
> accesses the hypervisor does: These won't have the intended effect
> anymore. Even worse, for PCIe devices (but not SR-IOV virtual
> functions) such accesses may (will?) be treated as Unsupported
> Requests, causing respective errors to be surfaced, potentially in the
> form of NMIs that may be fatal to the hypervisor or Dom0 is different
> ways. Hence rather than carrying out these accesses, we should avoid
> them where we can, and use alternative (e.g. PCI config space based)
> mechanisms to achieve at least the same effect.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>