On Thu, Oct 15, 2009 at 03:21:43PM -0700, Ed Swierk wrote:
> [Repost; the patch was garbled in my previous attempt.]
>
> Support for Xen PV-on-HVM guests can be implemented almost entirely in
> userspace, except for handling one annoying MSR that maps a Xen
> hypercall blob into guest address space.
>
> A generic mechanism to delegate MSR writes to userspace seems overkill
> and risks encouraging similar MSR abuse in the future. Thus this patch
> adds special support for the Xen HVM MSR.
>
> I implemented a new ioctl, KVM_XEN_HVM_CONFIG, that lets userspace tell
> KVM which MSR the guest will write to, as well as the starting address
> and size of the hypercall blobs (one each for 32-bit and 64-bit) that
> userspace has loaded from files. When the guest writes to the MSR, KVM
> copies one page of the blob from userspace to the guest.
>
> I've tested this patch with a hacked-up version of Gerd's userspace
> code, booting a number of guests (CentOS 5.3 i386 and x86_64, and
> FreeBSD 8.0-RC1 amd64) and exercising PV network and block devices.
>
> v3: separate blob_{addr,size}_{32,64}; move xen_hvm_config to struct
> kvm_arch; remove unneeded ifdefs; return -EFAULT, -E2BIG, etc. from
> xen_hvm_config; use is_long_mode(); remove debug printks; document ioctl
> in api.txt
>
> Signed-off-by: Ed Swierk <[email protected]>
Applied, thanks.
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