diff options
| author | David Gibson <dwg@au1.ibm.com> | 2011-06-29 00:22:41 +0000 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-07-12 13:16:56 +0300 |
| commit | 54738c097163c3f01e67ccc85462b78d4d4f495f (patch) | |
| tree | cba8d389d50251856cbe967c16ba2193a30d6d12 /arch/powerpc/include/asm/kvm_ppc.h | |
| parent | a8606e20e41a8149456bafdf76ad29d47672027c (diff) | |
KVM: PPC: Accelerate H_PUT_TCE by implementing it in real mode
This improves I/O performance for guests using the PAPR
paravirtualization interface by making the H_PUT_TCE hcall faster, by
implementing it in real mode. H_PUT_TCE is used for updating virtual
IOMMU tables, and is used both for virtual I/O and for real I/O in the
PAPR interface.
Since this moves the IOMMU tables into the kernel, we define a new
KVM_CREATE_SPAPR_TCE ioctl to allow qemu to create the tables. The
ioctl returns a file descriptor which can be used to mmap the newly
created table. The qemu driver models use them in the same way as
userspace managed tables, but they can be updated directly by the
guest with a real-mode H_PUT_TCE implementation, reducing the number
of host/guest context switches during guest IO.
There are certain circumstances where it is useful for userland qemu
to write to the TCE table even if the kernel H_PUT_TCE path is used
most of the time. Specifically, allowing this will avoid awkwardness
when we need to reset the table. More importantly, we will in the
future need to write the table in order to restore its state after a
checkpoint resume or migration.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch/powerpc/include/asm/kvm_ppc.h')
| -rw-r--r-- | arch/powerpc/include/asm/kvm_ppc.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h index 2afe92e6f62..99f6fcf4cf8 100644 --- a/arch/powerpc/include/asm/kvm_ppc.h +++ b/arch/powerpc/include/asm/kvm_ppc.h @@ -119,6 +119,8 @@ extern long kvmppc_prepare_vrma(struct kvm *kvm, extern void kvmppc_map_vrma(struct kvm *kvm, struct kvm_userspace_memory_region *mem); extern int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu); +extern long kvm_vm_ioctl_create_spapr_tce(struct kvm *kvm, + struct kvm_create_spapr_tce *args); extern int kvmppc_core_init_vm(struct kvm *kvm); extern void kvmppc_core_destroy_vm(struct kvm *kvm); extern int kvmppc_core_prepare_memory_region(struct kvm *kvm, |