File 0058-Revert-target-i386-kvm-add-VMX-migr.patch of Package qemu-linux-user

Overview Repositories Revisions Requests Users Attributes Meta

File 0058-Revert-target-i386-kvm-add-VMX-migr.patch of Package qemu-linux-user

From: Bruce Rogers <brogers@suse.com>
Date: Fri, 15 Feb 2019 15:12:04 -0700
Subject: Revert "target/i386: kvm: add VMX migration blocker"

This reverts commit d98f26073bebddcd3da0ba1b86c3a34e840c0fb8.
Here is some text explaining the revert:
I've thought about this some more, and with upstream
discussions about it having stagnated, at this point I think
the best solution is to revert the patch which considers it
a migration blocker to have the vmx feature enabled. It's
worth noting that not only are migrations blocked, but
saving of the vm state via save/restore and snapshots.

Given that it is still widely known that Nested Virtualization
is not supported by SUSE and other vendors, but is still used
by quite a few people who understand that there are caveats
with it's usage, I believe this migration blocker is more
hurtful than helpful.

The fact that as of the v4.20 kernel, nested virtualization is
enabled by default (for vmx), was partly why the patch was
added in the first place. But my perspective is that perhaps
enabling nested was still a bit premature.

I will make sure our qemu changelog explains that despite
removing that migration blocker, the user is warned that
nested virtualization is still a "use at your own risk
feature".

[BR: BSC#1121604]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 target/i386/kvm.c | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index b2401d13ea..f97bfc164d 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -855,7 +855,6 @@ static int hyperv_init_vcpu(X86CPU *cpu)
 }
 
 static Error *invtsc_mig_blocker;
-static Error *vmx_mig_blocker;
 
 #define KVM_MAX_CPUID_ENTRIES  100
 
@@ -1248,17 +1247,6 @@ int kvm_arch_init_vcpu(CPUState *cs)
                                   !!(c->ecx & CPUID_EXT_SMX);
     }
 
-    if ((env->features[FEAT_1_ECX] & CPUID_EXT_VMX) && !vmx_mig_blocker) {
-        error_setg(&vmx_mig_blocker,
-                   "Nested VMX virtualization does not support live migration yet");
-        r = migrate_add_blocker(vmx_mig_blocker, &local_err);
-        if (local_err) {
-            error_report_err(local_err);
-            error_free(vmx_mig_blocker);
-            return r;
-        }
-    }
-
     if (env->mcg_cap & MCG_LMCE_P) {
         has_msr_mcg_ext_ctl = has_msr_feature_control = true;
     }

Places

File 0058-Revert-target-i386-kvm-add-VMX-migr.patch of Package qemu-linux-user

Places