Stratos-dev March 2023

stratos-dev@op-lists.linaro.org

3 participants
5 discussions

[PATCH] libxl: arm: Allow grant mappings for backends running on Dom0

by Viresh Kumar

Currently, we add grant mapping related device tree properties if the backend domain is not Dom0. While Dom0 is privileged and can do foreign mapping for the entire guest memory, it is still okay for Dom0 to access guest's memory via grant mappings and hence map only what is required. This commit adds another parameter for virtio devices, with which they can do forced grant mappings irrespective of the backend domain id. Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org> --- docs/man/xl.cfg.5.pod.in | 4 ++++ tools/libs/light/libxl_arm.c | 21 ++++++++++++--------- tools/libs/light/libxl_types.idl | 1 + tools/libs/light/libxl_virtio.c | 11 +++++++++++ tools/xl/xl_parse.c | 2 ++ 5 files changed, 30 insertions(+), 9 deletions(-) diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in index 10f37990be57..4879f136aab8 100644 --- a/docs/man/xl.cfg.5.pod.in +++ b/docs/man/xl.cfg.5.pod.in @@ -1616,6 +1616,10 @@ properties in the Device Tree, the type field must be set to "virtio,device". Specifies the transport mechanism for the Virtio device, only "mmio" is supported for now. +=item B<forced_grant=BOOLEAN> + +Allows Xen Grant memory mapping to be done from Dom0. + =back =item B<tee="STRING"> diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c index 97c80d7ed0fa..ec2f1844e9b3 100644 --- a/tools/libs/light/libxl_arm.c +++ b/tools/libs/light/libxl_arm.c @@ -922,7 +922,8 @@ static int make_xen_iommu_node(libxl__gc *gc, void *fdt) /* The caller is responsible to complete / close the fdt node */ static int make_virtio_mmio_node_common(libxl__gc *gc, void *fdt, uint64_t base, - uint32_t irq, uint32_t backend_domid) + uint32_t irq, uint32_t backend_domid, + bool forced_grant) { int res; gic_interrupt intr; @@ -945,7 +946,7 @@ static int make_virtio_mmio_node_common(libxl__gc *gc, void *fdt, uint64_t base, res = fdt_property(fdt, "dma-coherent", NULL, 0); if (res) return res; - if (backend_domid != LIBXL_TOOLSTACK_DOMID) { + if (forced_grant || backend_domid != LIBXL_TOOLSTACK_DOMID) { uint32_t iommus_prop[2]; iommus_prop[0] = cpu_to_fdt32(GUEST_PHANDLE_IOMMU); @@ -959,11 +960,12 @@ static int make_virtio_mmio_node_common(libxl__gc *gc, void *fdt, uint64_t base, } static int make_virtio_mmio_node(libxl__gc *gc, void *fdt, uint64_t base, - uint32_t irq, uint32_t backend_domid) + uint32_t irq, uint32_t backend_domid, + bool forced_grant) { int res; - res = make_virtio_mmio_node_common(gc, fdt, base, irq, backend_domid); + res = make_virtio_mmio_node_common(gc, fdt, base, irq, backend_domid, forced_grant); if (res) return res; return fdt_end_node(fdt); @@ -1019,11 +1021,11 @@ static int make_virtio_mmio_node_gpio(libxl__gc *gc, void *fdt) static int make_virtio_mmio_node_device(libxl__gc *gc, void *fdt, uint64_t base, uint32_t irq, const char *type, - uint32_t backend_domid) + uint32_t backend_domid, bool forced_grant) { int res; - res = make_virtio_mmio_node_common(gc, fdt, base, irq, backend_domid); + res = make_virtio_mmio_node_common(gc, fdt, base, irq, backend_domid, forced_grant); if (res) return res; /* Add device specific nodes */ @@ -1363,7 +1365,7 @@ static int libxl__prepare_dtb(libxl__gc *gc, libxl_domain_config *d_config, iommu_needed = true; FDT( make_virtio_mmio_node(gc, fdt, disk->base, disk->irq, - disk->backend_domid) ); + disk->backend_domid, false) ); } } @@ -1373,12 +1375,13 @@ static int libxl__prepare_dtb(libxl__gc *gc, libxl_domain_config *d_config, if (virtio->transport != LIBXL_VIRTIO_TRANSPORT_MMIO) continue; - if (virtio->backend_domid != LIBXL_TOOLSTACK_DOMID) + if (virtio->forced_grant || virtio->backend_domid != LIBXL_TOOLSTACK_DOMID) iommu_needed = true; FDT( make_virtio_mmio_node_device(gc, fdt, virtio->base, virtio->irq, virtio->type, - virtio->backend_domid) ); + virtio->backend_domid, + virtio->forced_grant) ); } /* diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl index c10292e0d7e3..cfbcd717dc7f 100644 --- a/tools/libs/light/libxl_types.idl +++ b/tools/libs/light/libxl_types.idl @@ -740,6 +740,7 @@ libxl_device_virtio = Struct("device_virtio", [ ("backend_domname", string), ("type", string), ("transport", libxl_virtio_transport), + ("forced_grant", bool), ("devid", libxl_devid), # Note that virtio-mmio parameters (irq and base) are for internal # use by libxl and can't be modified. diff --git a/tools/libs/light/libxl_virtio.c b/tools/libs/light/libxl_virtio.c index faada49e184e..e1f15344ef97 100644 --- a/tools/libs/light/libxl_virtio.c +++ b/tools/libs/light/libxl_virtio.c @@ -48,11 +48,13 @@ static int libxl__set_xenstore_virtio(libxl__gc *gc, uint32_t domid, flexarray_append_pair(back, "base", GCSPRINTF("%#"PRIx64, virtio->base)); flexarray_append_pair(back, "type", GCSPRINTF("%s", virtio->type)); flexarray_append_pair(back, "transport", GCSPRINTF("%s", transport)); + flexarray_append_pair(back, "forced_grant", GCSPRINTF("%u", virtio->forced_grant)); flexarray_append_pair(front, "irq", GCSPRINTF("%u", virtio->irq)); flexarray_append_pair(front, "base", GCSPRINTF("%#"PRIx64, virtio->base)); flexarray_append_pair(front, "type", GCSPRINTF("%s", virtio->type)); flexarray_append_pair(front, "transport", GCSPRINTF("%s", transport)); + flexarray_append_pair(front, "forced_grant", GCSPRINTF("%u", virtio->forced_grant)); return 0; } @@ -104,6 +106,15 @@ static int libxl__virtio_from_xenstore(libxl__gc *gc, const char *libxl_path, } } + tmp = NULL; + rc = libxl__xs_read_checked(gc, XBT_NULL, + GCSPRINTF("%s/forced_grant", be_path), &tmp); + if (rc) goto out; + + if (tmp) { + virtio->forced_grant = strtoul(tmp, NULL, 0); + } + tmp = NULL; rc = libxl__xs_read_checked(gc, XBT_NULL, GCSPRINTF("%s/type", be_path), &tmp); diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c index 1f6f47daf4e1..3e34da099785 100644 --- a/tools/xl/xl_parse.c +++ b/tools/xl/xl_parse.c @@ -1215,6 +1215,8 @@ static int parse_virtio_config(libxl_device_virtio *virtio, char *token) } else if (MATCH_OPTION("transport", token, oparg)) { rc = libxl_virtio_transport_from_string(oparg, &virtio->transport); if (rc) return rc; + } else if (MATCH_OPTION("forced_grant", token, oparg)) { + virtio->forced_grant = strtoul(oparg, NULL, 0); } else { fprintf(stderr, "Unknown string \"%s\" in virtio spec\n", token); return -1; -- 2.31.1.272.g89b43f80a514

1 year, 6 months

[PATCH V3 0/2] qemu: vhost-user: Support Xen memory mapping quirks

by Viresh Kumar

Hello, This patchset tries to update the vhost-user protocol to make it support special memory mapping required in case of Xen hypervisor. The first patch is mostly cleanup and second one introduces a new xen specific feature. V2->V3: - Remove the extra message and instead update the memory regions to carry additional data. - Drop the one region one mmap relationship and allow back-end to map only parts of a region at once, required for Xen grant mappings. - Additional cleanup patch 1/2. V1->V2: - Make the custom mmap feature Xen specific, instead of being generic. - Clearly define which memory regions are impacted by this change. - Allow VHOST_USER_SET_XEN_MMAP to be called multiple times. - Additional Bit(2) property in flags. Viresh Kumar (2): docs: vhost-user: Define memory region separately docs: vhost-user: Add Xen specific memory mapping support docs/interop/vhost-user.rst | 60 ++++++++++++++++++++++++------------- 1 file changed, 39 insertions(+), 21 deletions(-) -- 2.31.1.272.g89b43f80a514

1 year, 8 months

[PATCH] libxl: fix matching of generic virtio device

by Viresh Kumar

The strings won't be an exact match, and we are only looking to match the prefix here, i.e. "virtio,device". This is already done properly in libxl_virtio.c file, lets do the same here too. Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org> --- tools/libs/light/libxl_arm.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c index ddc7b2a15975..97c80d7ed0fa 100644 --- a/tools/libs/light/libxl_arm.c +++ b/tools/libs/light/libxl_arm.c @@ -1033,10 +1033,14 @@ static int make_virtio_mmio_node_device(libxl__gc *gc, void *fdt, uint64_t base, } else if (!strcmp(type, VIRTIO_DEVICE_TYPE_GPIO)) { res = make_virtio_mmio_node_gpio(gc, fdt); if (res) return res; - } else if (strcmp(type, VIRTIO_DEVICE_TYPE_GENERIC)) { - /* Doesn't match generic virtio device */ - LOG(ERROR, "Invalid type for virtio device: %s", type); - return -EINVAL; + } else { + int len = sizeof(VIRTIO_DEVICE_TYPE_GENERIC) - 1; + + if (strncmp(type, VIRTIO_DEVICE_TYPE_GENERIC, len)) { + /* Doesn't match generic virtio device */ + LOG(ERROR, "Invalid type for virtio device: %s", type); + return -EINVAL; + } } return fdt_end_node(fdt); -- 2.31.1.272.g89b43f80a514

1 year, 8 months

[PATCH V2] docs: vhost-user: Add Xen specific memory mapping support

by Viresh Kumar

The current model of memory mapping at the back-end works fine where a standard call to mmap() (for the respective file descriptor) is enough before the front-end can start accessing the guest memory. There are other complex cases though where the back-end needs more information and simple mmap() isn't enough. For example Xen, a type-1 hypervisor, currently supports memory mapping via two different methods, foreign-mapping (via /dev/privcmd) and grant-dev (via /dev/gntdev). In both these cases, the back-end needs to call mmap() and ioctl(), and need to pass extra information via the ioctl(), like the Xen domain-id of the guest whose memory we are trying to map. Add a new protocol feature, 'VHOST_USER_PROTOCOL_F_XEN_MMAP', which lets the back-end know about the additional memory mapping requirements. When this feature is negotiated, the front-end can send the 'VHOST_USER_SET_XEN_MMAP' message type to provide the additional information to the back-end. Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org> --- V1->V2: - Make the custom mmap feature Xen specific, instead of being generic. - Clearly define which memory regions are impacted by this change. - Allow VHOST_USER_SET_XEN_MMAP to be called multiple times. - Additional Bit(2) property in flags. docs/interop/vhost-user.rst | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 3f18ab424eb0..8be5f5eae941 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -258,6 +258,24 @@ Inflight description :queue size: a 16-bit size of virtqueues +Xen mmap description +^^^^^^^^^^^^^^^^^^^^ + ++-------+-------+ +| flags | domid | ++-------+-------+ + +:flags: 64-bit bit field + +- Bit 0 is set for Xen foreign memory memory mapping. +- Bit 1 is set for Xen grant memory memory mapping. +- Bit 2 is set if the back-end can directly map additional memory (like + descriptor buffers or indirect descriptors, which aren't part of already + shared memory regions) without the need of front-end sending an additional + memory region first. + +:domid: a 64-bit Xen hypervisor specific domain id. + C structure ----------- @@ -867,6 +885,7 @@ Protocol features #define VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS 14 #define VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS 15 #define VHOST_USER_PROTOCOL_F_STATUS 16 + #define VHOST_USER_PROTOCOL_F_XEN_MMAP 17 Front-end message types ----------------------- @@ -1422,6 +1441,23 @@ Front-end message types query the back-end for its device status as defined in the Virtio specification. +``VHOST_USER_SET_XEN_MMAP`` + :id: 41 + :equivalent ioctl: N/A + :request payload: Xen mmap description + :reply payload: N/A + + When the ``VHOST_USER_PROTOCOL_F_XEN_MMAP`` protocol feature has been + successfully negotiated, this message is submitted by the front-end to set the + Xen hypervisor specific memory mapping configurations at the back-end. These + configurations should be used to mmap memory regions, virtqueues, descriptors + and descriptor buffers. The front-end must send this message before any + memory-regions are sent to the back-end via ``VHOST_USER_SET_MEM_TABLE`` or + ``VHOST_USER_ADD_MEM_REG`` message types. The front-end can send this message + multiple times, if different mmap configurations are required for different + memory regions, where the most recent ``VHOST_USER_SET_XEN_MMAP`` must be used + by the back-end to map any newly shared memory regions. + Back-end message types ---------------------- -- 2.31.1.272.g89b43f80a514

1 year, 9 months

Re: [virtio-dev] [RFC QEMU] docs: vhost-user: Add custom memory mapping support

by Stefan Hajnoczi

Resend - for some reason my email didn't make it out. ----- Forwarded message from Stefan Hajnoczi <stefanha(a)redhat.com> ----- Date: Tue, 21 Feb 2023 10:17:01 -0500 From: Stefan Hajnoczi <stefanha(a)redhat.com> To: Viresh Kumar <viresh.kumar(a)linaro.org> Cc: qemu-devel(a)nongnu.org, virtio-dev(a)lists.oasis-open.org, "Michael S. Tsirkin" <mst(a)redhat.com>, Vincent Guittot <vincent.guittot(a)linaro.org>, Alex Bennée <alex.bennee(a)linaro.org>, stratos-dev(a)op-lists.linaro.org, Oleksandr Tyshchenko <olekstysh(a)gmail.com>, xen-devel(a)lists.xen.org, Andrew Cooper <andrew.cooper3(a)citrix.com>, Juergen Gross <jgross(a)suse.com>, Sebastien Boeuf <sebastien.boeuf(a)intel.com>, Liu Jiang <gerry(a)linux.alibaba.com>, Mathieu Poirier <mathieu.poirier(a)linaro.org> Subject: Re: [virtio-dev] [RFC QEMU] docs: vhost-user: Add custom memory mapping support Message-ID: <Y/TgbZLY894p4a1S@fedora> On Tue, Feb 21, 2023 at 03:20:41PM +0530, Viresh Kumar wrote: > The current model of memory mapping at the back-end works fine with > Qemu, where a standard call to mmap() for the respective file > descriptor, passed from front-end, is generally all we need to do before > the front-end can start accessing the guest memory. > > There are other complex cases though, where we need more information at > the backend and need to do more than just an mmap() call. For example, > Xen, a type-1 hypervisor, currently supports memory mapping via two > different methods, foreign-mapping (via /dev/privcmd) and grant-dev (via > /dev/gntdev). In both these cases, the back-end needs to call mmap() > followed by an ioctl() (or vice-versa), and need to pass extra > information via the ioctl(), like the Xen domain-id of the guest whose > memory we are trying to map. > > Add a new protocol feature, 'VHOST_USER_PROTOCOL_F_CUSTOM_MMAP', which > lets the back-end know about the additional memory mapping requirements. > When this feature is negotiated, the front-end can send the > 'VHOST_USER_CUSTOM_MMAP' message type to provide the additional > information to the back-end. > > Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org> > --- > docs/interop/vhost-user.rst | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) The alternative to an in-band approach is to configure these details out-of-band. For example, via command-line options to the vhost-user back-end: $ my-xen-device --mapping-type=foreign-mapping --domain-id=123 I was thinking about both approaches and don't see an obvious reason to choose one or the other. What do you think? > diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst > index 3f18ab424eb0..f2b1d705593a 100644 > --- a/docs/interop/vhost-user.rst > +++ b/docs/interop/vhost-user.rst > @@ -258,6 +258,23 @@ Inflight description > > :queue size: a 16-bit size of virtqueues > > +Custom mmap description > +^^^^^^^^^^^^^^^^^^^^^^^ > + > ++-------+-------+ > +| flags | value | > ++-------+-------+ > + > +:flags: 64-bit bit field > + > +- Bit 0 is Xen foreign memory access flag - needs Xen foreign memory mapping. > +- Bit 1 is Xen grant memory access flag - needs Xen grant memory mapping. > + > +:value: a 64-bit hypervisor specific value. > + > +- For Xen foreign or grant memory access, this is set with guest's xen domain > + id. This is highly Xen-specific. How about naming the feature XEN_MMAP instead of CUSTOM_MMAP? If someone needs to add other mmap data later, they should define their own struct instead of trying to squeeze into the same fields as Xen. There is an assumption in this design that a single VHOST_USER_CUSTOM_MMAP message provides the information necessary for all mmaps. Are you sure the limitation that every mmap belongs to the same domain will be workable in the future? > + > C structure > ----------- > > @@ -867,6 +884,7 @@ Protocol features > #define VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS 14 > #define VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS 15 > #define VHOST_USER_PROTOCOL_F_STATUS 16 > + #define VHOST_USER_PROTOCOL_F_CUSTOM_MMAP 17 > > Front-end message types > ----------------------- > @@ -1422,6 +1440,20 @@ Front-end message types > query the back-end for its device status as defined in the Virtio > specification. > > +``VHOST_USER_CUSTOM_MMAP`` Most vhost-user protocol messages have a verb like get/set/close/add/listen/etc. I suggest renaming this to VHOST_USER_SET_XEN_MMAP_INFO. > + :id: 41 > + :equivalent ioctl: N/A > + :request payload: Custom mmap description > + :reply payload: N/A > + > + When the ``VHOST_USER_PROTOCOL_F_CUSTOM_MMAP`` protocol feature has been > + successfully negotiated, this message is submitted by the front-end to > + notify the back-end of the special memory mapping requirements, that the > + back-end needs to take care of, while mapping any memory regions sent > + over by the front-end. The front-end must send this message before > + any memory-regions are sent to the back-end via ``VHOST_USER_SET_MEM_TABLE`` > + or ``VHOST_USER_ADD_MEM_REG`` message types. > + > > Back-end message types > ---------------------- > -- > 2.31.1.272.g89b43f80a514 > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: virtio-dev-unsubscribe(a)lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help(a)lists.oasis-open.org > ----- End forwarded message -----

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Stratos-dev March 2023