[kvm-unit-tests PATCH v8 2/8] s390x: add function to set DAT mode for all interrupts

[Nico Boehr <nrb@xxxxxxxxxxxxx>]

When toggling DAT or switch address space modes, it is likely that
interrupts should be handled in the same DAT or address space mode.

Add a function which toggles DAT and address space mode for all
interruptions, except restart interrupts.

Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
---
 lib/s390x/asm/arch_def.h  | 10 ++++++----
 lib/s390x/asm/interrupt.h |  2 ++
 lib/s390x/interrupt.c     | 35 +++++++++++++++++++++++++++++++++++
 lib/s390x/mmu.c           |  5 +++--
 4 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index f629b6d0a17f..5beaf15b57e7 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -84,10 +84,12 @@ struct cpu {
 	bool in_interrupt_handler;
 };
 
-#define AS_PRIM				0
-#define AS_ACCR				1
-#define AS_SECN				2
-#define AS_HOME				3
+enum address_space {
+	AS_PRIM = 0,
+	AS_ACCR = 1,
+	AS_SECN = 2,
+	AS_HOME = 3
+};
 
 #define PSW_MASK_DAT			0x0400000000000000UL
 #define PSW_MASK_IO			0x0200000000000000UL
diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
index 35c1145f0349..d01f8a89641a 100644
--- a/lib/s390x/asm/interrupt.h
+++ b/lib/s390x/asm/interrupt.h
@@ -83,6 +83,8 @@ void expect_ext_int(void);
 uint16_t clear_pgm_int(void);
 void check_pgm_int_code(uint16_t code);
 
+void irq_set_dat_mode(bool use_dat, enum address_space as);
+
 /* Activate low-address protection */
 static inline void low_prot_enable(void)
 {
diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
index 3f993a363ae2..e990c1863630 100644
--- a/lib/s390x/interrupt.c
+++ b/lib/s390x/interrupt.c
@@ -9,6 +9,7 @@
  */
 #include <libcflat.h>
 #include <asm/barrier.h>
+#include <asm/mem.h>
 #include <asm/asm-offsets.h>
 #include <sclp.h>
 #include <interrupt.h>
@@ -104,6 +105,40 @@ void register_ext_cleanup_func(void (*f)(struct stack_frame_int *))
 	THIS_CPU->ext_cleanup_func = f;
 }
 
+/**
+ * irq_set_dat_mode - Set the DAT mode of all interrupt handlers, except for
+ * restart.
+ * @use_dat: specifies whether to use DAT or not
+ * @as: specifies the address space mode to use. Not set if use_dat is false.
+ *
+ * This will update the DAT mode and address space mode of all interrupt new
+ * PSWs.
+ *
+ * Since enabling DAT needs initialized CRs and the restart new PSW is often used
+ * to initialize CRs, the restart new PSW is never touched to avoid the chicken
+ * and egg situation.
+ */
+void irq_set_dat_mode(bool use_dat, enum address_space as)
+{
+	struct psw* irq_psws[] = {
+		OPAQUE_PTR(GEN_LC_EXT_NEW_PSW),
+		OPAQUE_PTR(GEN_LC_SVC_NEW_PSW),
+		OPAQUE_PTR(GEN_LC_PGM_NEW_PSW),
+		OPAQUE_PTR(GEN_LC_MCCK_NEW_PSW),
+		OPAQUE_PTR(GEN_LC_IO_NEW_PSW),
+	};
+	struct psw *psw;
+
+	assert(as == AS_PRIM || as == AS_ACCR || as == AS_SECN || as == AS_HOME);
+
+	for (size_t i = 0; i < ARRAY_SIZE(irq_psws); i++) {
+		psw = irq_psws[i];
+		psw->dat = use_dat;
+		if (use_dat)
+			psw->as = as;
+	}
+}
+
 static void fixup_pgm_int(struct stack_frame_int *stack)
 {
 	/* If we have an error on SIE we directly move to sie_exit */
diff --git a/lib/s390x/mmu.c b/lib/s390x/mmu.c
index b474d7021d3f..9a179d6b8ec5 100644
--- a/lib/s390x/mmu.c
+++ b/lib/s390x/mmu.c
@@ -12,6 +12,7 @@
 #include <asm/pgtable.h>
 #include <asm/arch_def.h>
 #include <asm/barrier.h>
+#include <asm/interrupt.h>
 #include <vmalloc.h>
 #include "mmu.h"
 
@@ -41,8 +42,8 @@ static void mmu_enable(pgd_t *pgtable)
 	/* enable dat (primary == 0 set as default) */
 	enable_dat();
 
-	/* we can now also use DAT unconditionally in our PGM handler */
-	lowcore.pgm_new_psw.mask |= PSW_MASK_DAT;
+	/* we can now also use DAT in all interrupt handlers */
+	irq_set_dat_mode(true, AS_PRIM);
 }
 
 /*
-- 
2.41.0