[kvm-unit-tests,v4,2/6] s390x: add function to set DAT mode for all interrupts

Commit Message

Nico Boehr July 11, 2023, 7:35 a.m. UTC

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 <[e-mail]>
---
 lib/s390x/asm/interrupt.h |  4 ++++
 lib/s390x/interrupt.c     | 35 +++++++++++++++++++++++++++++++++++
 lib/s390x/mmu.c           |  5 +++--
 3 files changed, 42 insertions(+), 2 deletions(-)

Comments

Nico Boehr July 12, 2023, 10:36 a.m. UTC | #1

Quoting Nico Boehr (2023-07-11 09:35:10)
[...]
> diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
> index 3f993a363ae2..d97b5a3a7e97 100644
> --- a/lib/s390x/interrupt.c
> +++ b/lib/s390x/interrupt.c
[...]
> +void irq_set_dat_mode(bool dat, uint64_t 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),
> +               NULL /* sentinel */
> +       };
> +
> +       assert(as == AS_PRIM || as == AS_ACCR || as == AS_SECN || as == AS_HOME);
> +
> +       for (struct psw *psw = irq_psws[0]; psw != NULL; psw++) {

This is obviously completely wrong and leads to a bunch of random memory in
lowcore being overwritten. For weird optimization reasons, this actually
terminates. I will sent a fixed version, where I simply don't do fancy pointer
stuff but just iterate over an array index...

Thanks Claudio.

Patch

diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
index 35c1145f0349..55759002dce2 100644
--- a/lib/s390x/asm/interrupt.h
+++ b/lib/s390x/asm/interrupt.h
@@ -83,6 +83,10 @@  void expect_ext_int(void);
 uint16_t clear_pgm_int(void);
 void check_pgm_int_code(uint16_t code);
 
+#define IRQ_DAT_ON	true
+#define IRQ_DAT_OFF	false
+void irq_set_dat_mode(bool dat, uint64_t 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..d97b5a3a7e97 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.
+ * This will update the DAT mode and address space mode of all interrupt new
+ * PSWs.
+ *
+ * Since enabling DAT needs initalized CRs and the restart new PSW is often used
+ * to initalize CRs, the restart new PSW is never touched to avoid the chicken
+ * and egg situation.
+ *
+ * @dat specifies whether to use DAT or not
+ * @as specifies the address space mode to use - one of AS_PRIM, AS_ACCR,
+ * AS_SECN or AS_HOME.
+ */
+void irq_set_dat_mode(bool dat, uint64_t 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),
+		NULL /* sentinel */
+	};
+
+	assert(as == AS_PRIM || as == AS_ACCR || as == AS_SECN || as == AS_HOME);
+
+	for (struct psw *psw = irq_psws[0]; psw != NULL; psw++) {
+		psw->dat = dat;
+		if (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..199bd3fbc9c8 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(IRQ_DAT_ON, AS_PRIM);
 }
 
 /*