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| author | Ed Swierk <eswierk@aristanetworks.com> | 2009-10-16 02:21:43 +0400 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-12-03 10:32:18 +0300 |
| commit | ffde22ac53b6d6b1d7206f1172176a667eead778 (patch) | |
| tree | 16ab77d364ba26928136e6d18463845941b6dd2c /Documentation/kvm | |
| parent | 94c30d9ca6fd00a69e367b91b6e13572c41938c5 (diff) | |
| download | linux-ffde22ac53b6d6b1d7206f1172176a667eead778.tar.xz | |
KVM: Xen PV-on-HVM guest support
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.
[jan: fix i386 build warning]
[avi: future proof abi with a flags field]
Signed-off-by: Ed Swierk <eswierk@aristanetworks.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'Documentation/kvm')
| -rw-r--r-- | Documentation/kvm/api.txt | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt index 5a4bc8cf6d04..3e8684e48506 100644 --- a/Documentation/kvm/api.txt +++ b/Documentation/kvm/api.txt @@ -593,6 +593,30 @@ struct kvm_irqchip { } chip; }; +4.27 KVM_XEN_HVM_CONFIG + +Capability: KVM_CAP_XEN_HVM +Architectures: x86 +Type: vm ioctl +Parameters: struct kvm_xen_hvm_config (in) +Returns: 0 on success, -1 on error + +Sets the MSR that the Xen HVM guest uses to initialize its hypercall +page, and provides the starting address and size of the hypercall +blobs in userspace. When the guest writes the MSR, kvm copies one +page of a blob (32- or 64-bit, depending on the vcpu mode) to guest +memory. + +struct kvm_xen_hvm_config { + __u32 flags; + __u32 msr; + __u64 blob_addr_32; + __u64 blob_addr_64; + __u8 blob_size_32; + __u8 blob_size_64; + __u8 pad2[30]; +}; + 5. The kvm_run structure Application code obtains a pointer to the kvm_run structure by |