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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 /drivers/s390/char/sclp_cmd.c | |
| parent | d8368af8b46b904def42a0f341d2f4f29001fa77 (diff) | |
| download | lwn-1526bf9ccf310f1d35c1275b8b477a249d25aaf2.tar.gz lwn-1526bf9ccf310f1d35c1275b8b477a249d25aaf2.zip | |
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/char/sclp_cmd.c')
| -rw-r--r-- | drivers/s390/char/sclp_cmd.c | 12 |
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. |