Currently, the grant mapping related device tree properties are added if the backend domain is not Dom0. While Dom0 is privileged and can do foreign mapping for the entire guest memory, it is still desired for Dom0 to access guest's memory via grant mappings and hence map only what is required.

This commit adds the "grant_usage" parameter for virtio devices, which provides better control over the functionality.

Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- V1->V2:

- Instead of just 0 or 1, the argument can take multiple values now and control the functionality in a better way.

- Update .gen.go files as well.

- Don't add nodes under frontend path.

docs/man/xl.cfg.5.pod.in | 12 ++++++++++++ tools/golang/xenlight/helpers.gen.go | 2 ++ tools/golang/xenlight/types.gen.go | 8 ++++++++ tools/libs/light/libxl_arm.c | 27 ++++++++++++++++++--------- tools/libs/light/libxl_types.idl | 7 +++++++ tools/libs/light/libxl_virtio.c | 19 +++++++++++++++++++ tools/xl/xl_parse.c | 3 +++ 7 files changed, 69 insertions(+), 9 deletions(-)

diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in index 24ac92718288..0405f6efe62a 100644 --- a/docs/man/xl.cfg.5.pod.in +++ b/docs/man/xl.cfg.5.pod.in @@ -1619,6 +1619,18 @@ hexadecimal format, without the "0x" prefix and all in lower case, like Specifies the transport mechanism for the Virtio device, only "mmio" is supported for now.

+=item B<grant_usage=STRING> + +Specifies the grant usage details for the Virtio device. This can be set to +following values: + +- "default": The default grant setting will be used, enable grants if + backend-domid != 0. + +- "enabled": The grants are always enabled. + +- "disabled": The grants are always disabled. + =back

=item B<tee="STRING"> diff --git a/tools/golang/xenlight/helpers.gen.go b/tools/golang/xenlight/helpers.gen.go index 0a203d22321f..71d9c24e382c 100644 --- a/tools/golang/xenlight/helpers.gen.go +++ b/tools/golang/xenlight/helpers.gen.go @@ -1792,6 +1792,7 @@ func (x *DeviceVirtio) fromC(xc *C.libxl_device_virtio) error { x.BackendDomname = C.GoString(xc.backend_domname) x.Type = C.GoString(xc._type) x.Transport = VirtioTransport(xc.transport) +x.GrantUsage = VirtioGrantUsage(xc.grant_usage) x.Devid = Devid(xc.devid) x.Irq = uint32(xc.irq) x.Base = uint64(xc.base) @@ -1809,6 +1810,7 @@ xc.backend_domname = C.CString(x.BackendDomname)} if x.Type != "" { xc._type = C.CString(x.Type)} xc.transport = C.libxl_virtio_transport(x.Transport) +xc.grant_usage = C.libxl_virtio_grant_usage(x.GrantUsage) xc.devid = C.libxl_devid(x.Devid) xc.irq = C.uint32_t(x.Irq) xc.base = C.uint64_t(x.Base) diff --git a/tools/golang/xenlight/types.gen.go b/tools/golang/xenlight/types.gen.go index a7c17699f80e..8f7234d3494a 100644 --- a/tools/golang/xenlight/types.gen.go +++ b/tools/golang/xenlight/types.gen.go @@ -261,6 +261,13 @@ VirtioTransportUnknown VirtioTransport = 0 VirtioTransportMmio VirtioTransport = 1 )

+type VirtioGrantUsage int +const( +VirtioGrantUsageDefault VirtioGrantUsage = 0 +VirtioGrantUsageDisabled VirtioGrantUsage = 1 +VirtioGrantUsageEnabled VirtioGrantUsage = 2 +) + type Passthrough int const( PassthroughDefault Passthrough = 0 @@ -683,6 +690,7 @@ BackendDomid Domid BackendDomname string Type string Transport VirtioTransport +GrantUsage VirtioGrantUsage Devid Devid Irq uint32 Base uint64 diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c index 97c80d7ed0fa..9cd7dbef0237 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 use_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 (use_grant) { 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 use_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, use_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 use_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, use_grant); if (res) return res;

/* Add device specific nodes */ @@ -1363,22 +1365,29 @@ 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, + disk->backend_domid != LIBXL_TOOLSTACK_DOMID) ); } }

for (i = 0; i < d_config->num_virtios; i++) { libxl_device_virtio *virtio = &d_config->virtios[i]; + bool use_grant = false;

if (virtio->transport != LIBXL_VIRTIO_TRANSPORT_MMIO) continue;

- if (virtio->backend_domid != LIBXL_TOOLSTACK_DOMID) + if ((virtio->grant_usage == LIBXL_VIRTIO_GRANT_USAGE_ENABLED) || + ((virtio->grant_usage == LIBXL_VIRTIO_GRANT_USAGE_DEFAULT) && + (virtio->backend_domid != LIBXL_TOOLSTACK_DOMID))) { + use_grant = true; iommu_needed = true; + }

FDT( make_virtio_mmio_node_device(gc, fdt, virtio->base, virtio->irq, virtio->type, - virtio->backend_domid) ); + virtio->backend_domid, + use_grant) ); }

/* diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl index c10292e0d7e3..17228817f9b7 100644 --- a/tools/libs/light/libxl_types.idl +++ b/tools/libs/light/libxl_types.idl @@ -283,6 +283,12 @@ libxl_virtio_transport = Enumeration("virtio_transport", [ (1, "MMIO"), ])

+libxl_virtio_grant_usage = Enumeration("virtio_grant_usage", [ + (0, "DEFAULT"), + (1, "DISABLED"), + (2, "ENABLED"), + ]) + libxl_passthrough = Enumeration("passthrough", [ (0, "default"), (1, "disabled"), @@ -740,6 +746,7 @@ libxl_device_virtio = Struct("device_virtio", [ ("backend_domname", string), ("type", string), ("transport", libxl_virtio_transport), + ("grant_usage", libxl_virtio_grant_usage), ("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 eadcb7124c3f..0a0fae967a0f 100644 --- a/tools/libs/light/libxl_virtio.c +++ b/tools/libs/light/libxl_virtio.c @@ -46,11 +46,13 @@ static int libxl__set_xenstore_virtio(libxl__gc *gc, uint32_t domid, flexarray_t *ro_front) { const char *transport = libxl_virtio_transport_to_string(virtio->transport); + const char *grant_usage = libxl_virtio_grant_usage_to_string(virtio->grant_usage);

flexarray_append_pair(back, "irq", GCSPRINTF("%u", virtio->irq)); 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, "grant_usage", GCSPRINTF("%s", grant_usage));

return 0; } @@ -102,6 +104,23 @@ 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/grant_usage", be_path), &tmp); + if (rc) goto out; + + if (!tmp || !strcmp(tmp, "default")) { + virtio->grant_usage = LIBXL_VIRTIO_GRANT_USAGE_DEFAULT; + } else { + if (!strcmp(tmp, "enabled")) { + virtio->grant_usage = LIBXL_VIRTIO_GRANT_USAGE_ENABLED; + } else if (!strcmp(tmp, "disabled")) { + virtio->grant_usage = LIBXL_VIRTIO_GRANT_USAGE_DISABLED; + } else { + return ERROR_INVAL; + } + } + 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..d2de3abfcd78 100644 --- a/tools/xl/xl_parse.c +++ b/tools/xl/xl_parse.c @@ -1215,6 +1215,9 @@ 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("grant_usage", token, oparg)) { + rc = libxl_virtio_grant_usage_from_string(oparg, &virtio->grant_usage); + if (rc) return rc; } else { fprintf(stderr, "Unknown string "%s" in virtio spec\n", token); return -1;

On Thu, May 11, 2023 at 01:20:42PM +0530, Viresh Kumar wrote:

The libxl_virtio file works for only PV devices and the nodes under the

Well, VirtIO devices are a kind of PV devices, yes, like there's Xen PV devices. So this explanation doesn't really make much sense.

frontend path are not used by anyone. Remove them.

Instead of describing what isn't used, it might be better to describe what we try to achieve. Something like:

Only the VirtIO backend will watch xenstore to find out when a new instance needs to be created for a guest, and read the parameters from there. VirtIO frontend are only virtio, so they will not do anything with the xenstore nodes. They can be removed.

While at it, also add a comment to the file describing what devices this file is used for.

Signed-off-by: Viresh Kumar viresh.kumar@linaro.org

V2: New patch.

tools/libs/light/libxl_virtio.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/tools/libs/light/libxl_virtio.c b/tools/libs/light/libxl_virtio.c index faada49e184e..eadcb7124c3f 100644 --- a/tools/libs/light/libxl_virtio.c +++ b/tools/libs/light/libxl_virtio.c @@ -10,6 +10,9 @@

• but WITHOUT ANY WARRANTY; without even the implied warranty of
• MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
• GNU Lesser General Public License for more details.

• • This is used for PV (paravirtualized) devices only and the frontend isn't
• • aware of the xenstore.

It might be more common to put this kind of comment at the top, that is just before the "Copyright" line.

Also, same remark as for the patch description, VirtIO are PV devices, so the comment is unnecessary. What is less obvious is why is there even xenstore interaction with a VirtIO device?

Maybe a better description for the source file would be:

Setup VirtIO backend. This is intended to interact with a VirtIO backend that is watching xenstore, and create new VirtIO devices with the parameter found in xenstore. (VirtIO frontend don't interact with xenstore.)

Thanks,