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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2012-05-15 16:15:25 +0400 |
|---|---|---|
| committer | Marcelo Tosatti <mtosatti@redhat.com> | 2012-05-18 04:06:01 +0400 |
| commit | 1526bf9ccf310f1d35c1275b8b477a249d25aaf2 (patch) | |
| tree | 61c7b138818c52df2dfcdc8a58ee891b198f424e /arch/s390 | |
| parent | d8368af8b46b904def42a0f341d2f4f29001fa77 (diff) | |
| download | linux-1526bf9ccf310f1d35c1275b8b477a249d25aaf2.tar.xz | |
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')
| -rw-r--r-- | arch/s390/include/asm/sclp.h | 1 | ||||
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 4 |
2 files changed, 5 insertions, 0 deletions
diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h index fed7bee650a0..bf238c55740b 100644 --- a/arch/s390/include/asm/sclp.h +++ b/arch/s390/include/asm/sclp.h @@ -48,6 +48,7 @@ int sclp_cpu_deconfigure(u8 cpu); void sclp_facilities_detect(void); unsigned long long sclp_get_rnmax(void); unsigned long long sclp_get_rzm(void); +u8 sclp_get_fac85(void); int sclp_sdias_blk_count(void); int sclp_sdias_copy(void *dest, int blk_num, int nr_blks); int sclp_chp_configure(struct chp_id chpid); 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; } |