On Mon, 2007-08-27 at 22:54 +0300, Avi Kivity wrote: > Anthony Liguori wrote: > > This adds a CPUID entry for the paravirtualization feature bitmap. We can > > do > > this unconditionally because the guest requires that both the feature CPUID > > entry and the signature CPUID entry exists to enable paravirtualization. > > > > This means that guest will never enable paravirtualization if either > > userspace > > or kernelspace doesn't support paravirtualization. > > > > Signed-off-by: Anthony Liguori <[EMAIL PROTECTED]> > > > > diff --git a/qemu/qemu-kvm.c b/qemu/qemu-kvm.c > > index 491c32c..1c93388 100644 > > --- a/qemu/qemu-kvm.c > > +++ b/qemu/qemu-kvm.c > > @@ -1103,12 +1103,18 @@ static void do_cpuid_ent(struct kvm_cpuid_entry *e, > > uint32_t function, > > int kvm_qemu_init_env(CPUState *cenv) > > { > > struct kvm_cpuid_entry cpuid_ent[100]; > > + struct kvm_cpuid_entry *pv_features; > > int cpuid_nent = 0; > > CPUState copy; > > uint32_t i, limit; > > > > copy = *cenv; > > > > + pv_features = &cpuid_ent[cpuid_nent++]; > > + memset(pv_features, 0, sizeof(*pv_features)); > > + pv_features->function = 0x40000003; > > + pv_features->eax = (1 << KVM_PARA_FEATURE_NOP_IO_DELAY); > > + > > copy.regs[R_EAX] = 0; > > qemu_kvm_cpuid_on_env(©); > > limit = copy.regs[R_EAX]; > > > > Shouldn't we query kvm here to see if the feature is needed?
I don't think so. At the moment, PIO goes to QEMU so QEMU is really the only one that should be making that decision. > I imagine I/O delay is never needed unless we passthrough a device, > which this qemu doesn't support, but it would be nice to set a good > example for the future. In this particular case, it would be a bad example since the kernel isn't the one that ought to be making the decision. I suspect PCI pass-through should be initiated in QEMU anyway so it still will be the one making the decision. However, if you apply these patches before my flight levels tomorrow, I can send out the MMU optimization patches that include a proper example of how to query kernel-space ;-) Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel