amd64_edac: Improve error injection

When injecting DRAM ECC errors over the F3xB[8,C] interface, the machine
does this by injecting the error in the next non-cached access. This
takes relatively long time on a normal system so that in order for us to
expedite it, we disable the caches around the injection.
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>

drivers/edac/amd64_edac.c

@@ -60,8 +60,8 @@ struct scrubrate {
 	{ 0x00, 0UL},        /* scrubbing off */
 };
 
-static int __amd64_read_pci_cfg_dword(struct pci_dev *pdev, int offset,
-				      u32 *val, const char *func)
+int __amd64_read_pci_cfg_dword(struct pci_dev *pdev, int offset,
+			       u32 *val, const char *func)
 {
 	int err = 0;
 
@@ -1980,11 +1980,11 @@ static void amd64_handle_ue(struct mem_ctl_info *mci, struct mce *m)
 static inline void __amd64_decode_bus_error(struct mem_ctl_info *mci,
 					    struct mce *m)
 {
-	u16 ec = EC(m->status);
-	u8 xec = XEC(m->status, 0x1f);
 	u8 ecc_type = (m->status >> 45) & 0x3;
+	u8 xec = XEC(m->status, 0x1f);
+	u16 ec = EC(m->status);
 
-	/* Bail early out if this was an 'observed' error */
+	/* Bail out early if this was an 'observed' error */
 	if (PP(ec) == NBSL_PP_OBS)
 		return;
 

drivers/edac/amd64_edac.h

@@ -273,9 +273,10 @@
 #define SET_NB_ARRAY_ADDR(section)	(((section) & 0x3) << 1)
 
 #define F10_NB_ARRAY_DATA		0xBC
+#define F10_NB_ARR_ECC_WR_REQ		BIT(17)
 #define SET_NB_DRAM_INJECTION_WRITE(inj)  \
 					(BIT(((inj.word) & 0xF) + 20) | \
-					BIT(17) | inj.bit_map)
+					F10_NB_ARR_ECC_WR_REQ | inj.bit_map)
 #define SET_NB_DRAM_INJECTION_READ(inj)  \
 					(BIT(((inj.word) & 0xF) + 20) | \
 					BIT(16) |  inj.bit_map)
@@ -306,9 +307,9 @@ enum amd_families {
 
 /* Error injection control structure */
 struct error_injection {
-	u32	section;
-	u32	word;
-	u32	bit_map;
+	u32	 section;
+	u32	 word;
+	u32	 bit_map;
 };
 
 /* low and high part of PCI config space regs */
@@ -460,6 +461,8 @@ struct amd64_family_type {
 	struct low_ops ops;
 };
 
+int __amd64_read_pci_cfg_dword(struct pci_dev *pdev, int offset,
+			       u32 *val, const char *func);
 int __amd64_write_pci_cfg_dword(struct pci_dev *pdev, int offset,
 				u32 val, const char *func);
 
@@ -476,3 +479,15 @@ int amd64_get_dram_hole_info(struct mem_ctl_info *mci, u64 *hole_base,
 			     u64 *hole_offset, u64 *hole_size);
 
 #define to_mci(k) container_of(k, struct mem_ctl_info, dev)
+
+/* Injection helpers */
+static inline void disable_caches(void *dummy)
+{
+	write_cr0(read_cr0() | X86_CR0_CD);
+	wbinvd();
+}
+
+static inline void enable_caches(void *dummy)
+{
+	write_cr0(read_cr0() & ~X86_CR0_CD);
+}

drivers/edac/amd64_edac_inj.c

@@ -153,8 +153,8 @@ static ssize_t amd64_inject_write_store(struct device *dev,
 {
 	struct mem_ctl_info *mci = to_mci(dev);
 	struct amd64_pvt *pvt = mci->pvt_info;
+	u32 section, word_bits, tmp;
 	unsigned long value;
-	u32 section, word_bits;
 	int ret;
 
 	ret = strict_strtoul(data, 10, &value);
@@ -168,9 +168,25 @@ static ssize_t amd64_inject_write_store(struct device *dev,
 
 	word_bits = SET_NB_DRAM_INJECTION_WRITE(pvt->injection);
 
+	pr_notice_once("Don't forget to decrease MCE polling interval in\n"
+			"/sys/bus/machinecheck/devices/machinecheck<CPUNUM>/check_interval\n"
+			"so that you can get the error report faster.\n");
+
+	on_each_cpu(disable_caches, NULL, 1);
+
 	/* Issue 'word' and 'bit' along with the READ request */
 	amd64_write_pci_cfg(pvt->F3, F10_NB_ARRAY_DATA, word_bits);
 
+ retry:
+	/* wait until injection happens */
+	amd64_read_pci_cfg(pvt->F3, F10_NB_ARRAY_DATA, &tmp);
+	if (tmp & F10_NB_ARR_ECC_WR_REQ) {
+		cpu_relax();
+		goto retry;
+	}
+
+	on_each_cpu(enable_caches, NULL, 1);
+
 	edac_dbg(0, "section=0x%x word_bits=0x%x\n", section, word_bits);
 
 	return count;