Messages in this thread | | | Date | Sun, 16 Sep 2007 11:08:24 +0200 | From | Avi Kivity <> | Subject | Re: [PATCH] Refactor hypercall infrastructure (v2) |
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Anthony Liguori wrote: > This patch refactors the current hypercall infrastructure to better support live > migration and SMP. It eliminates the hypercall page by trapping the UD > exception that would occur if you used the wrong hypercall instruction for the > underlying architecture and replacing it with the right one lazily. > > It also introduces the infrastructure to probe for hypercall available via > CPUID leaves 0x40001000. CPUID leaf 0x40001001 should be filled out by > userspace. > > A fall-out of this patch is that the unhandled hypercalls no longer trap to > userspace. There is very little reason though to use a hypercall to communicate > with userspace as PIO or MMIO can be used. There is no code in tree that uses > userspace hypercalls. > > Since the last patchset, I've changed the CPUID leaves to better avoid Xen's > CPUID range and fixed a bug spotted by Muli in masking off hypercall arguments. > > Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> > > @@ -1721,6 +1657,18 @@ void kvm_emulate_cpuid(struct kvm_vcpu *vcpu) > vcpu->regs[VCPU_REGS_RBX] = 0; > vcpu->regs[VCPU_REGS_RCX] = 0; > vcpu->regs[VCPU_REGS_RDX] = 0; > + > + if (function == KVM_CPUID_SIGNATURE) { > + u32 signature[3]; > + > + memcpy(signature, "LinuxPVLinux", 12); > + vcpu->regs[VCPU_REGS_RAX] = 0; > + vcpu->regs[VCPU_REGS_RBX] = signature[0]; > + vcpu->regs[VCPU_REGS_RCX] = signature[1]; > + vcpu->regs[VCPU_REGS_RDX] = signature[2]; > + goto out; > + } > + >
This needs to be done from userspace, so that kvm can pretend not to have this leaf.
(I have no objection to our userspace doing it unconditionally; but I don't want to force it on others)
Also, the signature string is too generic.
> diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c > index 18c2b2c..1362082 100644 > --- a/drivers/kvm/x86_emulate.c > +++ b/drivers/kvm/x86_emulate.c >
Please split out the emulator changes.
> - * > - * 64-bit parameters 1-6 are in the standard gcc x86_64 calling convention > - * order: RDI, RSI, RDX, RCX, R8, R9. > - * > - * 32-bit index is EBX, parameters are: EAX, ECX, EDX, ESI, EDI, EBP. > - * (the first 3 are according to the gcc regparm calling convention) >
Please document the new ABI.
-- error compiling committee.c: too many arguments to function
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