[PATCH v3 01/11] s390/entry: Remove __GMAP_ASCE and use _PIF_GUEST_FAULT again

Claudio Imbrenda
2024-10-15T16:43:32Z

Now that the guest ASCE is passed as a parameter to __sie64a(),
_PIF_GUEST_FAULT can be used again to determine whether the fault was a
guest or host fault.

Since the guest ASCE will not be taken from the gmap pointer in lowcore
anymore, __GMAP_ASCE can be removed. For the same reason the guest
ASCE needs now to be saved into the cr1 save area unconditionally.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
---
arch/s390/include/asm/ptrace.h | 2 ++
arch/s390/kernel/asm-offsets.c | 2 --
arch/s390/kernel/entry.S | 26 ++++++++++++++------------
arch/s390/mm/fault.c | 6 ++----
4 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index 2ad9324f6338..788bc4467445 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -14,11 +14,13 @@
#define PIF_SYSCALL 0 /* inside a system call */
#define PIF_EXECVE_PGSTE_RESTART 1 /* restart execve for PGSTE binaries */
#define PIF_SYSCALL_RET_SET 2 /* return value was set via ptrace */
+#define PIF_GUEST_FAULT 3 /* indicates program check in sie64a */
#define PIF_FTRACE_FULL_REGS 4 /* all register contents valid (ftrace) */

#define _PIF_SYSCALL BIT(PIF_SYSCALL)
#define _PIF_EXECVE_PGSTE_RESTART BIT(PIF_EXECVE_PGSTE_RESTART)
#define _PIF_SYSCALL_RET_SET BIT(PIF_SYSCALL_RET_SET)
+#define _PIF_GUEST_FAULT BIT(PIF_GUEST_FAULT)
#define _PIF_FTRACE_FULL_REGS BIT(PIF_FTRACE_FULL_REGS)

#define PSW32_MASK_PER _AC(0x40000000, UL)
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 5529248d84fb..3a6ee5043761 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -13,7 +13,6 @@
#include <linux/purgatory.h>
#include <linux/pgtable.h>
#include <linux/ftrace.h>
-#include <asm/gmap.h>
#include <asm/stacktrace.h>

int main(void)
@@ -161,7 +160,6 @@ int main(void)
OFFSET(__LC_PGM_TDB, lowcore, pgm_tdb);
BLANK();
/* gmap/sie offsets */
- OFFSET(__GMAP_ASCE, gmap, asce);
OFFSET(__SIE_PROG0C, kvm_s390_sie_block, prog0c);
OFFSET(__SIE_PROG20, kvm_s390_sie_block, prog20);
/* kexec_sha_region */
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index d6d5317f768e..454841229ef4 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -327,13 +327,23 @@ SYM_CODE_START(pgm_check_handler)
GET_LC %r13
stpt __LC_SYS_ENTER_TIMER(%r13)
BPOFF
- lgr %r10,%r15
lmg %r8,%r9,__LC_PGM_OLD_PSW(%r13)
+ xgr %r10,%r10
+ xgr %r12,%r12
tmhh %r8,0x0001 # coming from user space?
jno .Lpgm_skip_asce
lctlg %c1,%c1,__LC_KERNEL_ASCE(%r13)
j 3f # -> fault in user space
.Lpgm_skip_asce:
+#if IS_ENABLED(CONFIG_KVM)
+ lg %r11,__LC_CURRENT(%r13)
+ tm __TI_sie(%r11),0xff
+ jz 1f
+ BPENTER __SF_SIE_FLAGS(%r15),_TIF_ISOLATE_BP_GUEST
+ SIEEXIT __SF_SIE_CONTROL(%r15),%r13
+ lg %r12,__SF_SIE_GUEST_ASCE(%r15)
+ lghi %r10,_PIF_GUEST_FAULT
+#endif
1: tmhh %r8,0x4000 # PER bit set in old PSW ?
jnz 2f # -> enabled, can't be a double fault
tm __LC_PGM_ILC+3(%r13),0x80 # check for per exception
@@ -344,21 +354,13 @@ SYM_CODE_START(pgm_check_handler)
CHECK_VMAP_STACK __LC_SAVE_AREA,%r13,4f
3: lg %r15,__LC_KERNEL_STACK(%r13)
4: la %r11,STACK_FRAME_OVERHEAD(%r15)
- xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
+ stg %r10,__PT_FLAGS(%r11)
+ stg %r12,__PT_CR1(%r11)
xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
stmg %r0,%r7,__PT_R0(%r11)
mvc __PT_R8(64,%r11),__LC_SAVE_AREA(%r13)
mvc __PT_LAST_BREAK(8,%r11),__LC_PGM_LAST_BREAK(%r13)
- stctg %c1,%c1,__PT_CR1(%r11)
-#if IS_ENABLED(CONFIG_KVM)
- ltg %r12,__LC_GMAP(%r13)
- jz 5f
- clc __GMAP_ASCE(8,%r12), __PT_CR1(%r11)
- jne 5f
- BPENTER __SF_SIE_FLAGS(%r10),_TIF_ISOLATE_BP_GUEST
- SIEEXIT __SF_SIE_CONTROL(%r10),%r13
-#endif
-5: stmg %r8,%r9,__PT_PSW(%r11)
+ stmg %r8,%r9,__PT_PSW(%r11)
# clear user controlled registers to prevent speculative use
xgr %r0,%r0
xgr %r1,%r1
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index ad8b0d6b77ea..a6cf33b0f339 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -68,15 +68,13 @@ early_initcall(fault_init);
static enum fault_type get_fault_type(struct pt_regs *regs)
{
union teid teid = { .val = regs->int_parm_long };
- struct gmap *gmap;

if (likely(teid.as == PSW_BITS_AS_PRIMARY)) {
if (user_mode(regs))
return USER_FAULT;
if (!IS_ENABLED(CONFIG_PGSTE))
return KERNEL_FAULT;
- gmap = (struct gmap *)get_lowcore()->gmap;
- if (gmap && gmap->asce == regs->cr1)
+ if (test_pt_regs_flag(regs, PIF_GUEST_FAULT))
return GMAP_FAULT;
return KERNEL_FAULT;
}
@@ -187,7 +185,7 @@ static void dump_fault_info(struct pt_regs *regs)
pr_cont("user ");
break;
case GMAP_FAULT:
- asce = ((struct gmap *)get_lowcore()->gmap)->asce;
+ asce = regs->cr1;
pr_cont("gmap ");
break;
case KERNEL_FAULT:
--
2.47.0