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authorChristian Borntraeger <borntraeger@de.ibm.com>2012-05-15 16:15:25 +0400
committerMarcelo Tosatti <mtosatti@redhat.com>2012-05-18 04:06:01 +0400
commit1526bf9ccf310f1d35c1275b8b477a249d25aaf2 (patch)
tree61c7b138818c52df2dfcdc8a58ee891b198f424e /drivers/s390
parentd8368af8b46b904def42a0f341d2f4f29001fa77 (diff)
downloadlinux-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 'drivers/s390')
-rw-r--r--drivers/s390/char/sclp_cmd.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index 231a1d85127b..032171e335e9 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -17,6 +17,7 @@
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/memory.h>
+#include <linux/module.h>
#include <linux/platform_device.h>
#include <asm/chpid.h>
#include <asm/sclp.h>
@@ -38,7 +39,8 @@ struct read_info_sccb {
u64 facilities; /* 48-55 */
u8 _reserved2[84 - 56]; /* 56-83 */
u8 fac84; /* 84 */
- u8 _reserved3[91 - 85]; /* 85-90 */
+ u8 fac85; /* 85 */
+ u8 _reserved3[91 - 86]; /* 86-90 */
u8 flags; /* 91 */
u8 _reserved4[100 - 92]; /* 92-99 */
u32 rnsize2; /* 100-103 */
@@ -51,6 +53,7 @@ static int __initdata early_read_info_sccb_valid;
u64 sclp_facilities;
static u8 sclp_fac84;
+static u8 sclp_fac85;
static unsigned long long rzm;
static unsigned long long rnmax;
@@ -112,6 +115,7 @@ void __init sclp_facilities_detect(void)
sccb = &early_read_info_sccb;
sclp_facilities = sccb->facilities;
sclp_fac84 = sccb->fac84;
+ sclp_fac85 = sccb->fac85;
rnmax = sccb->rnmax ? sccb->rnmax : sccb->rnmax2;
rzm = sccb->rnsize ? sccb->rnsize : sccb->rnsize2;
rzm <<= 20;
@@ -127,6 +131,12 @@ unsigned long long sclp_get_rzm(void)
return rzm;
}
+u8 sclp_get_fac85(void)
+{
+ return sclp_fac85;
+}
+EXPORT_SYMBOL_GPL(sclp_get_fac85);
+
/*
* This function will be called after sclp_facilities_detect(), which gets
* called from early.c code. Therefore the sccb should have valid contents.