[Xen-devel] [RFC PATCH] Drop error return if size mismatch is due to xcr0 settings

[Don Koch <dkoch@xxxxxxxxxxx>]

This prevents migration from 4.3 to 4.4 (or newer) xen on AMD machines, at
least.

Signed-off-by: Don Koch <dkoch@xxxxxxxxxxx>
---
The question I have is whether to drop just the error return, leaving
a warning which might be useful for debugging, or drop the entire test
and the assigment before it. I think it would be prudent to test for
desc->length > max_size (i.e. XSTATE_CPUID's ecx value).

Personally, I think the warning is useful and a check against the max
size test should print an error/warning message and return an error;
the latter would require a new function.

The change that introduced this was 4cc134444.

The following is the minimum change "fix."

 xen/arch/x86/hvm/hvm.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index f0e1edc..dfedfb3 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2041,7 +2041,6 @@ static int hvm_load_cpu_xsave_states(struct domain *d, 
hvm_domain_context_t *h)
         printk(XENLOG_G_WARNING
                "HVM%d.%d restore mismatch: xsave length %u > %u\n",
                d->domain_id, vcpuid, desc->length, size);
-        return -EOPNOTSUPP;
     }
     /* Checking finished */
 
-- 
1.8.3.1


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