On 05/06/2010 12:27 AM, Glauber Costa wrote:
Right now, we were using individual KVM_CAP entities to communicate
userspace about which cpuids we support. This is suboptimal, since it
generates a delay between the feature arriving in the host, and
being available at the guest.
A much better mechanism is to list para features in KVM_GET_SUPPORTED_CPUID.
This makes userspace automatically aware of what we provide. And if we
ever add a new cpuid bit in the future, we have to do that again,
which create some complexity and delay in feature adoption.
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1971,6 +1971,23 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
}
break;
}
+ case KVM_CPUID_SIGNATURE: {
+ char signature[12] = "KVMKVMKVM\0\0";
+ u32 *sigptr = (u32 *)signature;
+ entry->eax = 1;
Don't understand where the value for eax comes from. qemu-kvm-x86.c has 0.
@@ -2017,6 +2034,19 @@ static int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
for (func = 0x80000001; func<= limit&& nent< cpuid->nent; ++func)
do_cpuid_ent(&cpuid_entries[nent], func, 0,
&nent, cpuid->nent);
+
+
+
+ r = -E2BIG;
+ if (nent>= cpuid->nent)
+ goto out_free;
+
+ do_cpuid_ent(&cpuid_entries[nent], KVM_CPUID_SIGNATURE, 0,&nent,
+ cpuid->nent);
Need a check here too, or the next call can overflow. Would have been
better to make do_cpuid_ent() check and return an error.
+
+ do_cpuid_ent(&cpuid_entries[nent], KVM_CPUID_FEATURES, 0,&nent,
+ cpuid->nent);
+
r = -E2BIG;
if (nent>= cpuid->nent)
goto out_free;
--
error compiling committee.c: too many arguments to function
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