[kvm-unit-tests PATCH v4] s390x: Load reset psw on diag308 reset

[Janosch Frank <frankja@linux.ibm.com>]

On a diag308 subcode 0 CRs will be reset, so we need a PSW mask
without DAT. Also we need to set the short psw indication to be
compliant with the architecture.

Let's therefore define a reset PSW mask with 64 bit addressing and
short PSW indication that is compliant with architecture and use it.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 lib/s390x/asm-offsets.c  |  1 +
 lib/s390x/asm/arch_def.h |  4 +++-
 s390x/cstart64.S         | 24 +++++++++++++++++-------
 3 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/lib/s390x/asm-offsets.c b/lib/s390x/asm-offsets.c
index 4b213f8..61d2658 100644
--- a/lib/s390x/asm-offsets.c
+++ b/lib/s390x/asm-offsets.c
@@ -58,6 +58,7 @@ int main(void)
 	OFFSET(GEN_LC_SW_INT_FPRS, lowcore, sw_int_fprs);
 	OFFSET(GEN_LC_SW_INT_FPC, lowcore, sw_int_fpc);
 	OFFSET(GEN_LC_SW_INT_CRS, lowcore, sw_int_crs);
+	OFFSET(GEN_LC_SW_INT_PSW, lowcore, sw_int_psw);
 	OFFSET(GEN_LC_MCCK_EXT_SA_ADDR, lowcore, mcck_ext_sa_addr);
 	OFFSET(GEN_LC_FPRS_SA, lowcore, fprs_sa);
 	OFFSET(GEN_LC_GRS_SA, lowcore, grs_sa);
diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index 07d4e5e..cf6e1ca 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -79,7 +79,8 @@ struct lowcore {
 	uint32_t	sw_int_fpc;			/* 0x0300 */
 	uint8_t		pad_0x0304[0x0308 - 0x0304];	/* 0x0304 */
 	uint64_t	sw_int_crs[16];			/* 0x0308 */
-	uint8_t		pad_0x0310[0x11b0 - 0x0388];	/* 0x0388 */
+	struct psw	sw_int_psw;			/* 0x0388 */
+	uint8_t		pad_0x0310[0x11b0 - 0x0398];	/* 0x0398 */
 	uint64_t	mcck_ext_sa_addr;		/* 0x11b0 */
 	uint8_t		pad_0x11b8[0x1200 - 0x11b8];	/* 0x11b8 */
 	uint64_t	fprs_sa[16];			/* 0x1200 */
@@ -98,6 +99,7 @@ struct lowcore {
 	uint8_t		pad_0x1400[0x1800 - 0x1400];	/* 0x1400 */
 	uint8_t		pgm_int_tdb[0x1900 - 0x1800];	/* 0x1800 */
 } __attribute__ ((__packed__));
+_Static_assert(sizeof(struct lowcore) == 0x1900, "Lowcore size");
 
 #define PGM_INT_CODE_OPERATION			0x01
 #define PGM_INT_CODE_PRIVILEGED_OPERATION	0x02
diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index 4be20fc..86dd4c4 100644
--- a/s390x/cstart64.S
+++ b/s390x/cstart64.S
@@ -126,13 +126,18 @@ memsetxc:
 .globl diag308_load_reset
 diag308_load_reset:
 	SAVE_REGS
-	/* Save the first PSW word to the IPL PSW */
+	/* Backup current PSW mask, as we have to restore it on success */
 	epsw	%r0, %r1
-	st	%r0, 0
-	/* Store the address and the bit for 31 bit addressing */
-	larl    %r0, 0f
-	oilh    %r0, 0x8000
-	st      %r0, 0x4
+	st	%r0, GEN_LC_SW_INT_PSW
+	st	%r1, GEN_LC_SW_INT_PSW + 4
+	/* Load reset psw mask (short psw, 64 bit) */
+	lg	%r0, reset_psw
+	/* Load the success label address */
+	larl    %r1, 0f
+	/* Or it to the mask */
+	ogr	%r0, %r1
+	/* Store it at the reset PSW location (real 0x0) */
+	stg	%r0, 0
 	/* Do the reset */
 	diag    %r0,%r2,0x308
 	/* Failure path */
@@ -144,7 +149,10 @@ diag308_load_reset:
 	lctlg	%c0, %c0, 0(%r1)
 	RESTORE_REGS
 	lhi	%r2, 1
-	br	%r14
+	larl	%r0, 1f
+	stg	%r0, GEN_LC_SW_INT_PSW + 8
+	lpswe	GEN_LC_SW_INT_PSW
+1:	br	%r14
 
 .globl smp_cpu_setup_state
 smp_cpu_setup_state:
@@ -184,6 +192,8 @@ svc_int:
 	lpswe	GEN_LC_SVC_OLD_PSW
 
 	.align	8
+reset_psw:
+	.quad	0x0008000180000000
 initial_psw:
 	.quad	0x0000000180000000, clear_bss_start
 pgm_int_psw:
-- 
2.20.1