On 4/2/19 4:46 AM, Ján Tomko wrote:
On Tue, Apr 02, 2019 at 09:21:53AM +0200, Peter Krempa wrote:
On Tue, Mar 12, 2019 at 18:55:49 -0300, Daniel Henrique Barboza wrote:
The NVLink2 support in QEMU implements the detection of NVLink2
capable devices by verifying the attributes of the VFIO mem region
QEMU allocates for the NVIDIA GPUs. To properly allocate an
adequate amount of memLock, Libvirt needs this information before
a QEMU instance is even created, thus querying QEMU is not
possible and opening a VFIO window is too much.
An alternative is presented in this patch. Making the following
assumptions:
- if we want GPU RAM to be available in the guest, an NVLink2 bridge
must be passed through;
- an unknown PCI device can be classified as a NVLink2 bridge
if its device tree node has 'ibm,gpu', 'ibm,nvlink',
'ibm,nvlink-speed' and 'memory-region'.
This patch introduces a helper called @ppc64VFIODeviceIsNV2Bridge
that checks the device tree node of a given PCI device and
check if it meets the criteria to be a NVLink2 bridge. This
new function will be used in a follow-up patch that, using the
first assumption, will set up the rlimits of the guest
accordingly.
Signed-off-by: Daniel Henrique Barboza <danielhb413@xxxxxxxxx>
---
src/qemu/qemu_domain.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
disclaimer: This is a code review. I don't have much knowledge about
what you are trying to implement.
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 1659e88478..dcc92d253c 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -10398,6 +10398,35 @@
qemuDomainUpdateCurrentMemorySize(virDomainObjPtr vm)
}
+/**
+ * ppc64VFIODeviceIsNV2Bridge:
+ * @device: string with the PCI device address
+ *
+ * This function receives a string that represents a PCI device,
+ * such as '0004:04:00.0', and tells if the device is a NVLink2
+ * bridge.
+ */
+static bool
+ppc64VFIODeviceIsNV2Bridge(const char *device)
+{
+ const char *nvlink2Files[] = {"ibm,gpu", "ibm,nvlink",
+ "ibm,nvlink-speed",
"memory-region"};
+ char *file;
+ size_t i;
+
+ for (i = 0; i < 4; i++) {
Use ARRAY_CARDINALITY(nvlink2Files) instead of '4'.
+ if ((virAsprintf(&file, "/sys/bus/pci/devices/%s/of_node/%s",
+ device, nvlink2Files[i])) < 0)
+ return false;
+
+ if (!virFileExists(file))
+ return false;
memory allocated to 'file' is leaked in every loop and also at exit. You
can use VIR_AUTOFREE(char *) file above, but you need to free the
pointer also in every single loop.
Or just declare the file variable inside the loop, then it will be freed
after going out of scope every loop.
Thanks for this tip. I've used it in both patches to fix this leak inside
loop.
Jano
+ }
+
+ return true;
+}
This function is unused and static, this means the build will fail after
this patch.
+
+
/**
* getPPC64MemLockLimitBytes:
* @def: domain definition
--
2.20.1
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