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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] libxl: write IO ABI for disk frontends
On 23/04/13 22:25, Wei Liu wrote:
> This is a patch to forward-port a Xend behaviour. Xend writes IO ABI used for
> all frontends. Linux kernel before 2.6.26 relies on this behaviour otherwise
> it cannot boot. Blkfront after 2.6.26 writes that node itself, in which case
> it's just an overwrite of the existing node which should be OK.
>
> In fact Xend writes the ABI for all frontends including console and vif. But
> nowadays it seems only old disk frontends rely on that ABI node so that we
> only write the ABI for disk frontends in libxl, minimizing the impact. Also
> ARM guests should not have this problem because they have new disk frontend so
> the snippets of this workaround are compiled for X86 target only.
>
> Also cleaned up trailing whitespaces while I was there.
>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
> tools/libxc/xc_domain.c | 20 ++++++++++++++++++
> tools/libxc/xenctrl.h | 14 +++++++++++++
> tools/libxl/libxl.c | 12 +++++++++++
> tools/libxl/libxl_create.c | 49
> +++++++++++++++++++++++++++++++++++++++++++
> tools/libxl/libxl_types.idl | 7 ++++---
> 5 files changed, 99 insertions(+), 3 deletions(-)
>
> diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
> index 480ce91..c3d8e28 100644
> --- a/tools/libxc/xc_domain.c
> +++ b/tools/libxc/xc_domain.c
> @@ -379,6 +379,26 @@ int xc_domain_hvm_setcontext(xc_interface *xch,
> return ret;
> }
>
> +#if defined (__i386__) || (__x86_64__)
Could we define this for all guests even if we only use it on x86 right now?
> +/* get guest word width */
> +int xc_domain_getwidth(xc_interface *xch,
> + uint32_t domid,
> + uint32_t *guest_width)
> +{
> + int ret;
> + DECLARE_DOMCTL;
> +
> + domctl.domain = domid;
> + domctl.cmd = XEN_DOMCTL_get_address_size;
> +
> + ret = do_domctl(xch, &domctl);
> +
> + *guest_width = domctl.u.address_size.size;
> +
> + return ret;
> +}
> +#endif
> +
> int xc_vcpu_getcontext(xc_interface *xch,
> uint32_t domid,
> uint32_t vcpu,
> diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
> index 50853af..c02dc1f 100644
> --- a/tools/libxc/xenctrl.h
> +++ b/tools/libxc/xenctrl.h
> @@ -636,6 +636,20 @@ int xc_domain_hvm_setcontext(xc_interface *xch,
> uint8_t *hvm_ctxt,
> uint32_t size);
>
> +#if defined (__i386__) || (__x86_64__)
> +/**
> + * This function will return the guest word width
> + *
> + * @parm xch a handle to an open hypervisor interface
> + * @parm domid the domain to get address width for
> + * @parm guest_width word width for guest
> + * @return 0 on success, -ev on failure
> + */
> +int xc_domain_getwidth(xc_interface *xch,
> + uint32_t domid,
> + uint32_t *guest_width);
> +#endif
> +
> /**
> * This function returns information about the execution context of a
> * particular vcpu of a domain.
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 572c2c6..5b8c9dc 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -2156,6 +2156,18 @@ static void device_disk_add(libxl__egc *egc, uint32_t
> domid,
> flexarray_append(front, "device-type");
> flexarray_append(front, disk->is_cdrom ? "cdrom" : "disk");
>
> + /*
> + * Old PV kernels before 2.6.26 rely on tool stack to write disk
> native
> + * protocol to frontend node.
> + *
> + * New kernels write this node themselves. In that case it just
> + * overwrites an existing node which is OK.
> + */
> + if (disk->native_protocol) {
> + flexarray_append(front, "protocol");
> + flexarray_append(front, disk->native_protocol);
> + }
> +
> libxl__device_generic_add(gc, t, device,
> libxl__xs_kvs_of_flexarray(gc, back,
> back->count),
> libxl__xs_kvs_of_flexarray(gc, front,
> front->count));
> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> index 30a4507..7abcaf9 100644
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -23,6 +23,7 @@
> #include <xc_dom.h>
> #include <xenguest.h>
> #include <xen/hvm/hvm_info_table.h>
> +#include <xen/io/protocols.h>
>
> int libxl__domain_create_info_setdefault(libxl__gc *gc,
> libxl_domain_create_info *c_info)
> @@ -910,6 +911,54 @@ static void domcreate_rebuild_done(libxl__egc *egc,
> goto error_out;
> }
>
> +#if defined (__i386__) || (__x86_64__)
I would prefer to get the guest type (x86 or arm) from libxc if possible
and use that instead of a define, different compilers tend to have
different names for this macros.
> + /*
> + * Pass along the disk navtive protocol to disks so that the protocol can
> + * be written to frontend Xenstore node. This is a workaround for old PV
> + * kernels before 2.6.26.
> + *
> + * Newer blkfront will write that node itself. In that case frontend just
> + * rewrites the node as it sees fit.
> + *
> + * Note that Xend actually propagate this vaule to all frontends
> including
> + * console and vifs. As now this is only needed for disk frontend so here
> + * we minimize the impact.
> + *
> + * Presumably ARM guests don't have this problem, so this snippet is only
> + * compiled for X86 target.
> + */
> +
> + if (d_config->c_info.type == LIBXL_DOMAIN_TYPE_PV) {
There is no PVHVM (or HVM with PV drivers) support on Linux version
2.6.26 and earlier?
> + int i;
> + uint32_t guest_width;
> + const char *protocol = NULL;
> +
> + ret = xc_domain_getwidth(CTX->xch, domid, &guest_width);
> + if (ret) {
> + ret = ERROR_FAIL;
> + goto error_out;
> + }
> +
> + switch (guest_width) {
> + case 32: /* 32 bit guest */
> + protocol = XEN_IO_PROTO_ABI_X86_32;
> + break;
> + case 64: /* 64 bit guest */
> + protocol = XEN_IO_PROTO_ABI_X86_64;
> + break;
> + default:
> + LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
> + "invalid address size for domain: %u",
> + guest_width);
> + ret = ERROR_FAIL;
> + goto error_out;
> + }
> +
> + for (i = 0; i < d_config->num_disks; i++)
> + d_config->disks[i].native_protocol = strdup(protocol);
> + }
> +#endif
> +
> store_libxl_entry(gc, domid, &d_config->b_info);
>
> libxl__multidev_begin(ao, &dcs->multidev);
> diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> index 6cb6de6..22622a9 100644
> --- a/tools/libxl/libxl_types.idl
> +++ b/tools/libxl/libxl_types.idl
> @@ -274,7 +274,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
> ("disable_migrate", libxl_defbool),
> ("cpuid", libxl_cpuid_policy_list),
> ("blkdev_start", string),
> -
> +
> ("device_model_version", libxl_device_model_version),
> ("device_model_stubdomain", libxl_defbool),
> # if you set device_model you must set device_model_version too
> @@ -318,9 +318,9 @@ libxl_domain_build_info = Struct("domain_build_info",[
> ("keymap", string),
> ("sdl", libxl_sdl_info),
> ("spice",
> libxl_spice_info),
> -
> +
> ("gfx_passthru", libxl_defbool),
> -
> +
> ("serial", string),
> ("boot", string),
> ("usb", libxl_defbool),
> @@ -371,6 +371,7 @@ libxl_device_disk = Struct("device_disk", [
> ("removable", integer),
> ("readwrite", integer),
> ("is_cdrom", integer),
> + ("native_protocol", string),
> ])
>
> libxl_device_nic = Struct("device_nic", [
>
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