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| author | Alexey Kardashevskiy <aik@ozlabs.ru> | 2014-07-19 11:59:34 +0400 |
|---|---|---|
| committer | Alexander Graf <agraf@suse.de> | 2014-07-28 17:23:16 +0400 |
| commit | a0840240c0c6bcbac8f0f5db11f95c19aaf9b52f (patch) | |
| tree | 3b4a2c128db2ff01c5d646780f0e63fc78d84229 /arch/powerpc/include | |
| parent | b2677b8dd8de0dc1496ede4da09b9dfd59f15cea (diff) | |
| download | linux-a0840240c0c6bcbac8f0f5db11f95c19aaf9b52f.tar.xz | |
KVM: PPC: Book3S: Fix LPCR one_reg interface
Unfortunately, the LPCR got defined as a 32-bit register in the
one_reg interface. This is unfortunate because KVM allows userspace
to control the DPFD (default prefetch depth) field, which is in the
upper 32 bits. The result is that DPFD always get set to 0, which
reduces performance in the guest.
We can't just change KVM_REG_PPC_LPCR to be a 64-bit register ID,
since that would break existing userspace binaries. Instead we define
a new KVM_REG_PPC_LPCR_64 id which is 64-bit. Userspace can still use
the old KVM_REG_PPC_LPCR id, but it now only modifies those fields in
the bottom 32 bits that userspace can modify (ILE, TC and AIL).
If userspace uses the new KVM_REG_PPC_LPCR_64 id, it can modify DPFD
as well.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: stable@vger.kernel.org
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch/powerpc/include')
| -rw-r--r-- | arch/powerpc/include/uapi/asm/kvm.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/include/uapi/asm/kvm.h index 0e56d9e7b2d6..e0e49dbb145d 100644 --- a/arch/powerpc/include/uapi/asm/kvm.h +++ b/arch/powerpc/include/uapi/asm/kvm.h @@ -548,6 +548,7 @@ struct kvm_get_htab_header { #define KVM_REG_PPC_VRSAVE (KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb4) #define KVM_REG_PPC_LPCR (KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb5) +#define KVM_REG_PPC_LPCR_64 (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb5) #define KVM_REG_PPC_PPR (KVM_REG_PPC | KVM_REG_SIZE_U64 | 0xb6) /* Architecture compatibility level */ |