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From 8996236421b4adf090ac721e8d525953deb9687a Mon Sep 17 00:00:00 2001
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Message-Id: <8996236421b4adf090ac721e8d525953deb9687a@dist-git>
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From: Daniel Henrique Barboza <danielhb413@gmail.com>
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Date: Fri, 3 May 2019 13:54:52 +0200
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Subject: [PATCH] qemu_domain: NVLink2 bridge detection function for PPC64
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The NVLink2 support in QEMU implements the detection of NVLink2
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capable devices by verifying the attributes of the VFIO mem region
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QEMU allocates for the NVIDIA GPUs. To properly allocate an
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adequate amount of memLock, Libvirt needs this information before
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a QEMU instance is even created, thus querying QEMU is not
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possible and opening a VFIO window is too much.
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An alternative is presented in this patch. Making the following
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assumptions:
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- if we want GPU RAM to be available in the guest, an NVLink2 bridge
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must be passed through;
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- an unknown PCI device can be classified as a NVLink2 bridge
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if its device tree node has 'ibm,gpu', 'ibm,nvlink',
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'ibm,nvlink-speed' and 'memory-region'.
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This patch introduces a helper called @ppc64VFIODeviceIsNV2Bridge
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that checks the device tree node of a given PCI device and
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check if it meets the criteria to be a NVLink2 bridge. This
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new function will be used in a follow-up patch that, using the
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first assumption, will set up the rlimits of the guest
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accordingly.
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Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
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(cherry picked from commit cc9f03801c2618102027ddc4a988193ae290b651)
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https: //bugzilla.redhat.com/show_bug.cgi?id=1505998
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Signed-off-by: Erik Skultety <eskultet@redhat.com>
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Message-Id: <99efa386adcf68789b7c8cffda2ef24f5f47f0c4.1556884443.git.eskultet@redhat.com>
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Reviewed-by: Andrea Bolognani <abologna@redhat.com>
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---
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src/qemu/qemu_domain.c | 30 ++++++++++++++++++++++++++++++
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1 file changed, 30 insertions(+)
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diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
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index f91de0b743..a8bc618389 100644
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--- a/src/qemu/qemu_domain.c
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+++ b/src/qemu/qemu_domain.c
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@@ -9805,6 +9805,36 @@ qemuDomainUpdateCurrentMemorySize(virQEMUDriverPtr driver,
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}
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+/**
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+ * ppc64VFIODeviceIsNV2Bridge:
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+ * @device: string with the PCI device address
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+ *
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+ * This function receives a string that represents a PCI device,
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+ * such as '0004:04:00.0', and tells if the device is a NVLink2
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+ * bridge.
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+ */
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+static ATTRIBUTE_UNUSED bool
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+ppc64VFIODeviceIsNV2Bridge(const char *device)
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+{
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+ const char *nvlink2Files[] = {"ibm,gpu", "ibm,nvlink",
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+ "ibm,nvlink-speed", "memory-region"};
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+ size_t i;
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+
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+ for (i = 0; i < ARRAY_CARDINALITY(nvlink2Files); i++) {
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+ VIR_AUTOFREE(char *) file = NULL;
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+
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+ if ((virAsprintf(&file, "/sys/bus/pci/devices/%s/of_node/%s",
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+ device, nvlink2Files[i])) < 0)
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+ return false;
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+
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+ if (!virFileExists(file))
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+ return false;
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+ }
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+
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+ return true;
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+}
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+
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+
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/**
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* getPPC64MemLockLimitBytes:
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* @def: domain definition
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--
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2.21.0
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