powerpc/powernv: Call OPAL sync before kexec'ing

Its possible that OPAL may be writing to host memory during kexec (like dump retrieve scenario). In this situation we might end up corrupting host memory. This patch makes OPAL sync call to make sure OPAL stops writing to host memory before kexec'ing. Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Call OPAL sync before kexec'ing
Its possible that OPAL may be writing to host memory during kexec (like dump retrieve scenario). In this situation we might end up corrupting host memory. This patch makes OPAL sync call to make sure OPAL stops writing to host memory before kexec'ing. Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Vasant Hegde · Benjamin Herrenschmidt
1 parent cb5b242c8c
Showing 4 changed files with 23 additions and 2 deletions Side-by-side Diff
arch/powerpc/include/asm/opal.h
arch/powerpc/platforms/powernv/opal-wrappers.S
arch/powerpc/platforms/powernv/opal.c
arch/powerpc/platforms/powernv/setup.c
@@ -156,6 +156,7 @@
 #define OPAL_FLASH_UPDATE			78
 #define OPAL_GET_MSG				85
 #define OPAL_CHECK_ASYNC_COMPLETION		86
+#define OPAL_SYNC_HOST_REBOOT			87
  
 #ifndef __ASSEMBLY__
  
@@ -828,6 +829,7 @@
  
 int64_t opal_get_msg(uint64_t buffer, size_t size);
 int64_t opal_check_completion(uint64_t buffer, size_t size, uint64_t token);
+int64_t opal_sync_host_reboot(void);
  
 /* Internal functions */
 extern int early_init_dt_scan_opal(unsigned long node, const char *uname, int depth, void *data);
@@ -128,4 +128,5 @@
 OPAL_CALL(opal_update_flash,			OPAL_FLASH_UPDATE);
 OPAL_CALL(opal_get_msg,				OPAL_GET_MSG);
 OPAL_CALL(opal_check_completion,		OPAL_CHECK_ASYNC_COMPLETION);
+OPAL_CALL(opal_sync_host_reboot,		OPAL_SYNC_HOST_REBOOT);
@@ -20,6 +20,7 @@
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/kobject.h>
+#include <linux/delay.h>
 #include <asm/opal.h>
 #include <asm/firmware.h>
 #include <asm/mce.h>
  
  
@@ -482,11 +483,26 @@
 void opal_shutdown(void)
 {
 	unsigned int i;
+	long rc = OPAL_BUSY;
  
+	/* First free interrupts, which will also mask them */
 	for (i = 0; i < opal_irq_count; i++) {
 		if (opal_irqs[i])
 			free_irq(opal_irqs[i], NULL);
 		opal_irqs[i] = 0;
+	}
+
+	/*
+	 * Then sync with OPAL which ensure anything that can
+	 * potentially write to our memory has completed such
+	 * as an ongoing dump retrieval
+	 */
+	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
+		rc = opal_sync_host_reboot();
+		if (rc == OPAL_BUSY)
+			opal_poll_events(NULL);
+		else
+			mdelay(10);
 	}
 }
@@ -145,8 +145,10 @@
 	/* Let the PCI code clear up IODA tables */
 	pnv_pci_shutdown();
  
-	/* And unregister all OPAL interrupts so they don't fire
-	 * up while we kexec
+	/*
+	 * Stop OPAL activity: Unregister all OPAL interrupts so they
+	 * don't fire up while we kexec and make sure all potentially
+	 * DMA'ing ops are complete (such as dump retrieval).
 	 */
 	opal_shutdown();
 }
...	...	@@ -156,6 +156,7 @@
156	156	#define OPAL_FLASH_UPDATE 78
157	157	#define OPAL_GET_MSG 85
158	158	#define OPAL_CHECK_ASYNC_COMPLETION 86
	159	+#define OPAL_SYNC_HOST_REBOOT 87
159	160
160	161	#ifndef __ASSEMBLY__
161	162
...	...	@@ -828,6 +829,7 @@
828	829
829	830	int64_t opal_get_msg(uint64_t buffer, size_t size);
830	831	int64_t opal_check_completion(uint64_t buffer, size_t size, uint64_t token);
	832	+int64_t opal_sync_host_reboot(void);
831	833
832	834	/* Internal functions */
833	835	extern int early_init_dt_scan_opal(unsigned long node, const char uname, int depth, void data);
...	...	@@ -128,4 +128,5 @@
128	128	OPAL_CALL(opal_update_flash, OPAL_FLASH_UPDATE);
129	129	OPAL_CALL(opal_get_msg, OPAL_GET_MSG);
130	130	OPAL_CALL(opal_check_completion, OPAL_CHECK_ASYNC_COMPLETION);
	131	+OPAL_CALL(opal_sync_host_reboot, OPAL_SYNC_HOST_REBOOT);
...	...	@@ -20,6 +20,7 @@
20	20	#include <linux/slab.h>
21	21	#include <linux/sched.h>
22	22	#include <linux/kobject.h>
	23	+#include <linux/delay.h>
23	24	#include <asm/opal.h>
24	25	#include <asm/firmware.h>
25	26	#include <asm/mce.h>
26	27
27	28
...	...	@@ -482,11 +483,26 @@
482	483	void opal_shutdown(void)
483	484	{
484	485	unsigned int i;
	486	+ long rc = OPAL_BUSY;
485	487
	488	+ /* First free interrupts, which will also mask them */
486	489	for (i = 0; i < opal_irq_count; i++) {
487	490	if (opal_irqs[i])
488	491	free_irq(opal_irqs[i], NULL);
489	492	opal_irqs[i] = 0;
	493	+ }
	494	+
	495	+ /*
	496	+ * Then sync with OPAL which ensure anything that can
	497	+ * potentially write to our memory has completed such
	498	+ * as an ongoing dump retrieval
	499	+ */
	500	+ while (rc == OPAL_BUSY \|\| rc == OPAL_BUSY_EVENT) {
	501	+ rc = opal_sync_host_reboot();
	502	+ if (rc == OPAL_BUSY)
	503	+ opal_poll_events(NULL);
	504	+ else
	505	+ mdelay(10);
490	506	}
491	507	}
...	...	@@ -145,8 +145,10 @@
145	145	/* Let the PCI code clear up IODA tables */
146	146	pnv_pci_shutdown();
147	147
148		- /* And unregister all OPAL interrupts so they don't fire
149		- * up while we kexec
	148	+ /*
	149	+ * Stop OPAL activity: Unregister all OPAL interrupts so they
	150	+ * don't fire up while we kexec and make sure all potentially
	151	+ * DMA'ing ops are complete (such as dump retrieval).
150	152	*/
151	153	opal_shutdown();
152	154	}