[Qemu-devel] Re: [PATCH] kvm: Fix error detection for KVM_GET_DIRTY_LOG

[Jan Kiszka <jan.kiszka@web.de>]

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Anthony Liguori wrote:
> Jan Kiszka wrote:
>>> That makes me uncomfortable.  Shouldn't we make kvm return something
>>> that's exposed to userspace?
>>>
>>>     
>>
>> Yes, but we can't do this from user space :) (or in other words: there
>> are already kernels out there which return this invalid code).
>>   
> 
> But since it's not symbolic, at some point in time the meaning of 524
> can potentially change and introduce a very, very subtle bug.

I won't change in old kernel versions, and I expect someone from the PowerPC folks to fix it for new version fairly soon.

> 
>> The situation would only be different if Alex said that it takes further
>> kernel patches anyway to make his PowerPC targets work. Dunno.
>>   
> 
> Certainly, his PPC target is not in any released kernel version so
> there's time to fix things properly.

Ah, ok. Then let's do this (Alex can carry a temporary workaround
locally IMHO):

------------->

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---

 kvm-all.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index 824bb4c..5fb8dba 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -348,7 +348,7 @@ int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
         d.slot = mem->slot;
 
         r = kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d);
-        if (r == -EINVAL) {
+        if (r < 0) {
             dprintf("ioctl failed %d\n", errno);
             ret = -1;
             break;


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