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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 31/31] libxl: allow the creation of HVM domains without a device model.
El 07/08/15 a les 14.58, Wei Liu ha escrit:
> On Fri, Aug 07, 2015 at 12:18:08PM +0200, Roger Pau Monne wrote:
>> Replace the firmware loaded into HVM guests with an OS kernel. Since the HVM
>> builder now uses the PV xc_dom_* set of functions this kernel will be parsed
>> and loaded inside the guest like on PV, but the container is a pure HVM
>> guest.
>>
>> Also, if device_model_version is set to none or a device model for the
>> specified domain is not present unconditinally set the nic type to
>> LIBXL_NIC_TYPE_VIF.
>>
>> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
>> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
>> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
>> ---
>> Changes since v3:
>> - Add explicit /* fall through */ comments.
>> - Expand libxl__device_nic_setdefault so that it sets the right nic type
>> for HVMlite guests.
>> - Remove stray space in hvm_build_set_params.
>> - Fix the error paths of libxl__domain_firmware.
>> ---
>> docs/man/xl.cfg.pod.5 | 5 ++++
>> tools/libxc/xc_dom_x86.c | 7 +++++
>> tools/libxl/libxl.c | 39 ++++++++++++++-----------
>> tools/libxl/libxl_create.c | 16 ++++++++++-
>> tools/libxl/libxl_dm.c | 13 ++++++++-
>> tools/libxl/libxl_dom.c | 68
>> ++++++++++++++++++++++++++++++--------------
>> tools/libxl/libxl_internal.h | 5 +++-
>> tools/libxl/libxl_types.idl | 1 +
>> tools/libxl/libxl_x86.c | 4 ++-
>> tools/libxl/xl_cmdimpl.c | 2 ++
>> 10 files changed, 118 insertions(+), 42 deletions(-)
>>
>> diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
>> index 80e51bb..8cd7726 100644
>> --- a/docs/man/xl.cfg.pod.5
>> +++ b/docs/man/xl.cfg.pod.5
>> @@ -1741,6 +1741,11 @@ This device-model is the default for Linux dom0.
>> Use the device-model based upon the historical Xen fork of Qemu.
>> This device-model is still the default for NetBSD dom0.
>>
>> +=item B<none>
>> +
>> +Don't use any device model. This requires a kernel capable of booting
>> +in this mode.
>
> booting without emulated devices?
Yes, that's more clear.
>> +
>> =back
>>
>> It is recommended to accept the default value for new guests. If
>> diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
>> index 1599de4..d67feb0 100644
>> --- a/tools/libxc/xc_dom_x86.c
>> +++ b/tools/libxc/xc_dom_x86.c
>> @@ -1269,6 +1269,13 @@ static int meminit_hvm(struct xc_dom_image *dom)
>> if ( nr_pages > target_pages )
>> memflags |= XENMEMF_populate_on_demand;
>>
>> + /* Make sure there's a MMIO hole for the special pages. */
>> + if ( dom->mmio_size == 0 )
>> + {
>> + dom->mmio_size = NR_SPECIAL_PAGES << PAGE_SHIFT;
>> + dom->mmio_start = special_pfn(0);
>> + }
>> +
>
> Better to just assert(dom->mmio_size != 0);
>
> It's really libxl's responsibility to generate memory layout for guest.
> Libxc doesn't have all information to make the decision.
As said in a previous email, libxl doesn't know the size or position of
the special pages created by libxc code, so right now it's impossible
for libxl to create a correct mmio hole for a HVMlite guest.
>
>> if ( dom->nr_vmemranges == 0 )
>> {
>> /* Build dummy vnode information
>> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
>> index 083f099..a01868a 100644
>> --- a/tools/libxl/libxl.c
>> +++ b/tools/libxl/libxl.c
>> @@ -1033,11 +1033,13 @@ int libxl_domain_unpause(libxl_ctx *ctx, uint32_t
>> domid)
>> }
>>
>> if (type == LIBXL_DOMAIN_TYPE_HVM) {
>> - rc = libxl__domain_resume_device_model(gc, domid);
>> - if (rc < 0) {
>> - LOG(ERROR, "failed to unpause device model for domain %u:%d",
>> - domid, rc);
>> - goto out;
>> + if (libxl__domain_has_device_model(gc, domid)) {
>
> Checking for device model version is not enough?
Sadly we don't have access to the device model version here, and it is
not stored anywhere, so the only option I see is to actually check if
there's a device model running or not in order to figure out if we have
to unpause it.
>> + rc = libxl__domain_resume_device_model(gc, domid);
>> + if (rc < 0) {
>> + LOG(ERROR, "failed to unpause device model for domain
>> %u:%d",
>> + domid, rc);
>> + goto out;
>> + }
>> }
>> }
>> ret = xc_domain_unpause(ctx->xch, domid);
>> @@ -1567,7 +1569,6 @@ void libxl__destroy_domid(libxl__egc *egc,
>> libxl__destroy_domid_state *dis)
>> libxl_ctx *ctx = CTX;
>> uint32_t domid = dis->domid;
>> char *dom_path;
>> - char *pid;
>> int rc, dm_present;
>>
>> libxl__ev_child_init(&dis->destroyer);
>> @@ -1584,14 +1585,13 @@ void libxl__destroy_domid(libxl__egc *egc,
>> libxl__destroy_domid_state *dis)
>>
>> switch (libxl__domain_type(gc, domid)) {
>> case LIBXL_DOMAIN_TYPE_HVM:
>> - if (!libxl_get_stubdom_id(CTX, domid))
>> - dm_present = 1;
>> - else
>> + if (libxl_get_stubdom_id(CTX, domid)) {
>> dm_present = 0;
>> - break;
>> + break;
>> + }
>> + /* fall through */
>> case LIBXL_DOMAIN_TYPE_PV:
>> - pid = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc,
>> "/local/domain/%d/image/device-model-pid", domid));
>> - dm_present = (pid != NULL);
>> + dm_present = libxl__domain_has_device_model(gc, domid);
>> break;
>> case LIBXL_DOMAIN_TYPE_INVALID:
>> rc = ERROR_FAIL;
>> @@ -3203,7 +3203,7 @@ out:
>>
>> /******************************************************************************/
>>
>> int libxl__device_nic_setdefault(libxl__gc *gc, libxl_device_nic *nic,
>> - uint32_t domid)
>> + uint32_t domid, libxl_domain_build_info
>> *info)
>> {
>> int rc;
>>
>> @@ -3240,8 +3240,15 @@ int libxl__device_nic_setdefault(libxl__gc *gc,
>> libxl_device_nic *nic,
>>
>> switch (libxl__domain_type(gc, domid)) {
>> case LIBXL_DOMAIN_TYPE_HVM:
>> - if (!nic->nictype)
>> - nic->nictype = LIBXL_NIC_TYPE_VIF_IOEMU;
>> + if (!nic->nictype) {
>> + if (info != NULL &&
>> + info->device_model_version !=
>> LIBXL_DEVICE_MODEL_VERSION_NONE)
>> + nic->nictype = LIBXL_NIC_TYPE_VIF_IOEMU;
>> + else if (libxl__domain_has_device_model(gc, domid))
>> + nic->nictype = LIBXL_NIC_TYPE_VIF_IOEMU;
>> + else
>> + nic->nictype = LIBXL_NIC_TYPE_VIF;
>
> I think all you need is to pass in device model version and
>
> if version != none
> nictype = ioemu
> else
> nictype = vif
>
> ?
>
> Otherwise the code suggests that there can be case you have specified a
> device model when creating a domain but it somehow disappears when
> domain is running?
That's exactly the case. During domain creation we know if there's a
device model or not. But if we are doing a hot-attach of a nic this
information is not available, so the only solution I see is to actually
check for the device model presence.
Thanks for the review, Roger.
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