Re: [Qemu-devel] [RFC] Next gen kvm api

2012-02-15 Thread Arnd Bergmann
On Tuesday 07 February 2012, Alexander Graf wrote:
  
  Not sure we'll ever get there. For PPC, it will probably take another 1-2 
  years until we get the 32-bit targets stabilized. By then we will have new 
  64-bit support though. And then the next gen will come out giving us even 
  more new constraints.
  
  I would expect that newer archs have less constraints, not more.
 
 Heh. I doubt it :). The 64-bit booke stuff is pretty similar to what we have 
 today on 32-bit, but extends a
 bunch of registers to 64-bit. So what if we laid out stuff wrong before?
 
 I don't even want to imagine what v7 arm vs v8 arm looks like. It's a 
 completely new architecture.
 

I have not seen the source but I'm pretty sure that v7 and v8 they look very
similar regarding virtualization support because they were designed together,
including the concept that on v8 you can run either a v7 compatible 32 bit
hypervisor with 32 bit guests or a 64 bit hypervisor with a combination of
32 and 64 bit guests. Also, the page table layout in v7-LPAE is identical
to the v8 one. The main difference is the instruction set, but then ARMv7
already has four of these (ARM, Thumb, Thumb2, ThumbEE).

Arnd

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Re: [PATCH] KVM: Add compat ioctl for KVM_SET_SIGNAL_MASK

2011-06-07 Thread Arnd Bergmann
On Tuesday 07 June 2011 22:25:15 Alexander Graf wrote:
 +static long kvm_vcpu_compat_ioctl(struct file *filp,
 + unsigned int ioctl, unsigned long arg)
 +{
 +   struct kvm_vcpu *vcpu = filp-private_data;
 +   void __user *argp = (void __user *)arg;

Converting a compat user argument into a pointer should use the
compat_ptr() function to do the right thing on s390. Otherwise
your patch looks good.

Arnd
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Re: [PATCH 00/27] Add KVM support for Book3s_64 (PPC64) hosts v5

2009-10-22 Thread Arnd Bergmann
On Wednesday 21 October 2009, Alexander Graf wrote:
 
 KVM for PowerPC only supports embedded cores at the moment.
 
 While it makes sense to virtualize on small machines, it's even more fun
 to do so on big boxes. So I figured we need KVM for PowerPC64 as well.
 
 This patchset implements KVM support for Book3s_64 hosts and guest support
 for Book3s_64 and G3/G4.
 
 To really make use of this, you also need a recent version of qemu.
 
 
 Don't want to apply patches? Get the git tree!
 
 $ git clone git://csgraf.de/kvm
 $ git checkout origin/ppc-v4

Whole series Acked-by: Arnd Bergmann a...@arndb.de

Great work, Alex!

Arnd 
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Re: [PATCH 4/4] kvmppc: convert wrteei to wrtee as kvm guest optimization

2008-08-19 Thread Arnd Bergmann
On Tuesday 19 August 2008, [EMAIL PROTECTED] wrote:
 Dependent on the already existing CONFIG_KVM_GUEST config option this patch
 changes wrteei to wrtee allowing the hypervisor to rewrite those to 
 nontrapping
 instructions. Maybe we should split the kvm guest otpimizations in two parts
 one for the overhead free optimizations and on for the rest that might add
 some complexity for non virtualized execution (like this one).
 
 Signed-off-by: Christian Ehrhardt [EMAIL PROTECTED]

How significant is the performance impact of this change for non-virtualized
systems? If it's very low, maybe you should not bother with the #ifdef, and
if it's noticable, you might be better off using dynamic patching for this.

Arnd 
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