| Message ID | 1277508314-915-10-git-send-email-agraf@suse.de (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On 06/26/2010 02:24 AM, Alexander Graf wrote: > While running in hooked code we need to store register contents out because > we must not clobber any registers. > > So let's add some fields to the shared page we can just happily write to. > > How are these protected during interrupts?
Am 27.06.2010 um 10:22 schrieb Avi Kivity <avi@redhat.com>: > On 06/26/2010 02:24 AM, Alexander Graf wrote: >> While running in hooked code we need to store register contents out >> because >> we must not clobber any registers. >> >> So let's add some fields to the shared page we can just happily >> write to. >> >> > > How are these protected during interrupts? By the 'critical section' bit. When in a critical section (read: using scratch registers), we don't issue interrupts. Alex
On 06/27/2010 12:41 PM, Alexander Graf wrote: > > Am 27.06.2010 um 10:22 schrieb Avi Kivity <avi@redhat.com>: > >> On 06/26/2010 02:24 AM, Alexander Graf wrote: >>> While running in hooked code we need to store register contents out >>> because >>> we must not clobber any registers. >>> >>> So let's add some fields to the shared page we can just happily >>> write to. >>> >>> >> >> How are these protected during interrupts? > > By the 'critical section' bit. When in a critical section (read: using > scratch registers), we don't issue interrupts. Ok. I thought you needed scratch registers to set up the critical section, but you don't. Neat stuff.
diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h index d1fe9ae..edf8f83 100644 --- a/arch/powerpc/include/asm/kvm_para.h +++ b/arch/powerpc/include/asm/kvm_para.h @@ -23,6 +23,9 @@ #include <linux/types.h> struct kvm_vcpu_arch_shared { + __u64 scratch1; + __u64 scratch2; + __u64 scratch3; __u64 critical; /* Guest may not get interrupts if == r1 */ __u64 sprg0; __u64 sprg1;
While running in hooked code we need to store register contents out because we must not clobber any registers. So let's add some fields to the shared page we can just happily write to. Signed-off-by: Alexander Graf <agraf@suse.de> --- arch/powerpc/include/asm/kvm_para.h | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)