From e9418cec1ba24b6cf78f85bbbef8586ed612692a Mon Sep 17 00:00:00 2001
Message-Id: <e9418cec1ba24b6cf78f85bbbef8586ed612692a@dist-git>
From: =?UTF-8?q?J=C3=A1n=20Tomko?= <jtomko@redhat.com>
Date: Mon, 13 Mar 2023 13:56:47 +0100
Subject: [PATCH] qemu: relax shared memory check for vhostuser daemons
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For some vhostuser daemons, we validate that the guest memory is shared
with the host.

With earlier versions of QEMU, it was only possible to mark memory
as shared by defining an explicit NUMA topology.  Later, QEMU exposed
the name of the default memory backend (defaultRAMid) so we can mark
that memory as shared.

Since libvirt commit:
  commit bff2ad5d6b1f25da02802273934d2a519159fec7
    qemu: Relax validation for mem->access if guest has no NUMA
we already check for the case when user requests shared memory,
but QEMU did not expose defaultRAMid.

Drop the duplicit check from vhostuser device validation, to make
it pass on hotplug even after libvirtd restart.

This avoids the need to store the defaultRAMid, since we don't really
need it for anything after the VM has been already started.

https://bugzilla.redhat.com/show_bug.cgi?id=2078693
https://bugzilla.redhat.com/show_bug.cgi?id=2177701

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
(cherry picked from commit d5c7b7870e45575f81fffcb611c2546d0e02e778)
Signed-off-by: Ján Tomko <jtomko@redhat.com>
---
 src/qemu/qemu_validate.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
index 7bc14293d6..4069f47c12 100644
--- a/src/qemu/qemu_validate.c
+++ b/src/qemu/qemu_validate.c
@@ -1588,16 +1588,12 @@ qemuValidateDomainVirtioOptions(const virDomainVirtioOptions *virtio,
 static int
 qemuValidateDomainDefVhostUserRequireSharedMemory(const virDomainDef *def,
                                                   const char *name,
-                                                  virQEMUCaps *qemuCaps)
+                                                  virQEMUCaps *qemuCaps G_GNUC_UNUSED)
 {
-    const char *defaultRAMId = virQEMUCapsGetMachineDefaultRAMid(qemuCaps,
-                                                                 def->virtType,
-                                                                 def->os.machine);
     size_t numa_nodes = virDomainNumaGetNodeCount(def->numa);
     size_t i;
 
-    if (numa_nodes == 0 &&
-        !(defaultRAMId && def->mem.access == VIR_DOMAIN_MEMORY_ACCESS_SHARED)) {
+    if (numa_nodes == 0 && def->mem.access != VIR_DOMAIN_MEMORY_ACCESS_SHARED) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                        _("'%s' requires shared memory"), name);
         return -1;
-- 
2.40.1