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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2012-05-15 14:15:25 +0200 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-05-17 21:06:01 -0300 |
| commit | 1526bf9ccf310f1d35c1275b8b477a249d25aaf2 (patch) | |
| tree | 61c7b138818c52df2dfcdc8a58ee891b198f424e /arch/s390/kvm | |
| parent | d8368af8b46b904def42a0f341d2f4f29001fa77 (diff) | |
| download | linux-1526bf9ccf310f1d35c1275b8b477a249d25aaf2.tar.gz | |
KVM: s390: add capability indicating COW support
Currently qemu/kvm on s390 uses a guest mapping that does not allow the guest backing page table to be write-protected to support older systems. On those older systems a host write protection fault will be delivered to the guest. Newer systems allow to write-protect the guest backing memory and let the fault be delivered to the host, thus allowing COW. Use a capability bit to tell qemu if that is possible. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/s390/kvm')
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index e5e3800b0125..5c761bffa02d 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -28,6 +28,7 @@ #include <asm/pgtable.h> #include <asm/nmi.h> #include <asm/switch_to.h> +#include <asm/sclp.h> #include "kvm-s390.h" #include "gaccess.h" @@ -140,6 +141,9 @@ int kvm_dev_ioctl_check_extension(long ext) case KVM_CAP_MAX_VCPUS: r = KVM_MAX_VCPUS; break; + case KVM_CAP_S390_COW: + r = sclp_get_fac85() & 0x2; + break; default: r = 0; } |