[v1 2/5] s390/entry: sort out physical vs virtual pointers usage in sie64a

Nico Boehr
2022-10-20T14:32:12Z

Fix virtual vs physical address confusion (which currently are the
same).

sie_block is accessed in entry.S and passed it to hardware, which is why
both its physical and virtual address are needed. To avoid every caller
having to do the virtual-physical conversion, add a new function sie64a()
which converts the virtual address to physical.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
arch/s390/include/asm/kvm_host.h | 8 +++++++-
arch/s390/include/asm/stacktrace.h | 1 +
arch/s390/kernel/asm-offsets.c | 1 +
arch/s390/kernel/entry.S | 26 +++++++++++++++-----------
4 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index b1e98a9ed152..9a31d00e99b3 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -1017,7 +1017,13 @@ void kvm_arch_crypto_clear_masks(struct kvm *kvm);
void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
unsigned long *aqm, unsigned long *adm);

-extern int sie64a(struct kvm_s390_sie_block *, u64 *);
+int __sie64a(phys_addr_t sie_block_phys, struct kvm_s390_sie_block *sie_block, u64 *rsa);
+
+static inline int sie64a(struct kvm_s390_sie_block *sie_block, u64 *rsa)
+{
+ return __sie64a(virt_to_phys(sie_block), sie_block, rsa);
+}
+
extern char sie_exit;

extern int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc);
diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index b23c658dce77..1802be5abb5d 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -46,6 +46,7 @@ struct stack_frame {
unsigned long sie_savearea;
unsigned long sie_reason;
unsigned long sie_flags;
+ unsigned long sie_control_block_phys;
};
};
unsigned long gprs[10];
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index d8ce965c0a97..3f8e760298c2 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -62,6 +62,7 @@ int main(void)
OFFSET(__SF_SIE_SAVEAREA, stack_frame, sie_savearea);
OFFSET(__SF_SIE_REASON, stack_frame, sie_reason);
OFFSET(__SF_SIE_FLAGS, stack_frame, sie_flags);
+ OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys);
DEFINE(STACK_FRAME_OVERHEAD, sizeof(struct stack_frame));
BLANK();
/* idle data offsets */
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index d2a1f2f4f5b8..12e1773a94a4 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -225,18 +225,20 @@ ENDPROC(__switch_to)

#if IS_ENABLED(CONFIG_KVM)
/*
- * sie64a calling convention:
- * %r2 pointer to sie control block
- * %r3 guest register save area
+ * __sie64a calling convention:
+ * %r2 pointer to sie control block phys
+ * %r3 pointer to sie control block virt
+ * %r4 guest register save area
*/
-ENTRY(sie64a)
+ENTRY(__sie64a)
stmg %r6,%r14,__SF_GPRS(%r15) # save kernel registers
lg %r12,__LC_CURRENT
- stg %r2,__SF_SIE_CONTROL(%r15) # save control block pointer
- stg %r3,__SF_SIE_SAVEAREA(%r15) # save guest register save area
+ stg %r2,__SF_SIE_CONTROL_PHYS(%r15) # save sie block physical..
+ stg %r3,__SF_SIE_CONTROL(%r15) # ...and virtual addresses
+ stg %r4,__SF_SIE_SAVEAREA(%r15) # save guest register save area
xc __SF_SIE_REASON(8,%r15),__SF_SIE_REASON(%r15) # reason code = 0
mvc __SF_SIE_FLAGS(8,%r15),__TI_flags(%r12) # copy thread flags
- lmg %r0,%r13,0(%r3) # load guest gprs 0-13
+ lmg %r0,%r13,0(%r4) # load guest gprs 0-13
lg %r14,__LC_GMAP # get gmap pointer
ltgr %r14,%r14
jz .Lsie_gmap
@@ -248,6 +250,7 @@ ENTRY(sie64a)
jnz .Lsie_skip
TSTMSK __LC_CPU_FLAGS,_CIF_FPU
jo .Lsie_skip # exit if fp/vx regs changed
+ lg %r14,__SF_SIE_CONTROL_PHYS(%r15) # get sie block phys addr
BPEXIT __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
.Lsie_entry:
sie 0(%r14)
@@ -258,13 +261,14 @@ ENTRY(sie64a)
BPOFF
BPENTER __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
.Lsie_skip:
+ lg %r14,__SF_SIE_CONTROL(%r15) # get control block pointer
ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE
lctlg %c1,%c1,__LC_KERNEL_ASCE # load primary asce
.Lsie_done:
# some program checks are suppressing. C code (e.g. do_protection_exception)
# will rewind the PSW by the ILC, which is often 4 bytes in case of SIE. There
# are some corner cases (e.g. runtime instrumentation) where ILC is unpredictable.
-# Other instructions between sie64a and .Lsie_done should not cause program
+# Other instructions between __sie64a and .Lsie_done should not cause program
# interrupts. So lets use 3 nops as a landing pad for all possible rewinds.
.Lrewind_pad6:
nopr 7
@@ -293,8 +297,8 @@ sie_exit:
EX_TABLE(.Lrewind_pad4,.Lsie_fault)
EX_TABLE(.Lrewind_pad2,.Lsie_fault)
EX_TABLE(sie_exit,.Lsie_fault)
-ENDPROC(sie64a)
-EXPORT_SYMBOL(sie64a)
+ENDPROC(__sie64a)
+EXPORT_SYMBOL(__sie64a)
EXPORT_SYMBOL(sie_exit)
#endif

@@ -373,7 +377,7 @@ ENTRY(pgm_check_handler)
j 3f # -> fault in user space
.Lpgm_skip_asce:
#if IS_ENABLED(CONFIG_KVM)
- # cleanup critical section for program checks in sie64a
+ # cleanup critical section for program checks in __sie64a
OUTSIDE %r9,.Lsie_gmap,.Lsie_done,1f
SIEEXIT
lghi %r10,_PIF_GUEST_FAULT
--
2.37.3