cxl: Flush PSL cache before resetting the adapter

If the capi link is going down while the PSL owns a dirty cache line,
any access from the host for that data could lead to an Uncorrectable
Error.

So when resetting the capi adapter through sysfs, make sure the PSL
cache is flushed. It won't help if there are any active Process
Elements on the card, as the cache would likely get new dirty cache
lines immediately, but if resetting an idle adapter, it should avoid
any bad surprises from data left over from terminated Process Elements.

Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index 344a0ff8f8c7df97e5328f89e46cd3f55b791d68..01d372aba131416524ec565748ea4f9e52a795ee 100644 (file)
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -162,7 +162,10 @@ static const cxl_p2n_reg_t CXL_PSL_WED_An     = {0x0A0};
 #define CXL_PSL_SPAP_V    0x0000000000000001ULL
 
 /****** CXL_PSL_Control ****************************************************/
-#define CXL_PSL_Control_tb 0x0000000000000001ULL
+#define CXL_PSL_Control_tb              (0x1ull << (63-63))
+#define CXL_PSL_Control_Fr              (0x1ull << (63-31))
+#define CXL_PSL_Control_Fs_MASK         (0x3ull << (63-29))
+#define CXL_PSL_Control_Fs_Complete     (0x3ull << (63-29))
 
 /****** CXL_PSL_DLCNTL *****************************************************/
 #define CXL_PSL_DLCNTL_D (0x1ull << (63-28))
@@ -854,6 +857,7 @@ int cxl_register_one_irq(struct cxl *adapter, irq_handler_t handler,
 int cxl_check_error(struct cxl_afu *afu);
 int cxl_afu_slbia(struct cxl_afu *afu);
 int cxl_tlb_slb_invalidate(struct cxl *adapter);
+int cxl_data_cache_flush(struct cxl *adapter);
 int cxl_afu_disable(struct cxl_afu *afu);
 int cxl_psl_purge(struct cxl_afu *afu);
 

diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index e606fdc4bc9cc3ec0ff7d3f29d4e691c30a26bd4..a217a74ccc980d13f71577e46b151bf3f3397de7 100644 (file)
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -290,6 +290,37 @@ int cxl_tlb_slb_invalidate(struct cxl *adapter)
        return 0;
 }
 
+int cxl_data_cache_flush(struct cxl *adapter)
+{
+       u64 reg;
+       unsigned long timeout = jiffies + (HZ * CXL_TIMEOUT);
+
+       pr_devel("Flushing data cache\n");
+
+       reg = cxl_p1_read(adapter, CXL_PSL_Control);
+       reg |= CXL_PSL_Control_Fr;
+       cxl_p1_write(adapter, CXL_PSL_Control, reg);
+
+       reg = cxl_p1_read(adapter, CXL_PSL_Control);
+       while ((reg & CXL_PSL_Control_Fs_MASK) != CXL_PSL_Control_Fs_Complete) {
+               if (time_after_eq(jiffies, timeout)) {
+                       dev_warn(&adapter->dev, "WARNING: cache flush timed out!\n");
+                       return -EBUSY;
+               }
+
+               if (!cxl_ops->link_ok(adapter, NULL)) {
+                       dev_warn(&adapter->dev, "WARNING: link down when flushing cache\n");
+                       return -EIO;
+               }
+               cpu_relax();
+               reg = cxl_p1_read(adapter, CXL_PSL_Control);
+       }
+
+       reg &= ~CXL_PSL_Control_Fr;
+       cxl_p1_write(adapter, CXL_PSL_Control, reg);
+       return 0;
+}
+
 static int cxl_write_sstp(struct cxl_afu *afu, u64 sstp0, u64 sstp1)
 {
        int rc;

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index cd922a80bf9733597bb7ebdb0a8c4e5913dd78ee..7afad8477ad55358f3608abefcf85795407a99a1 100644 (file)
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1239,6 +1239,9 @@ int cxl_pci_reset(struct cxl *adapter)
 
        dev_info(&dev->dev, "CXL reset\n");
 
+       /* the adapter is about to be reset, so ignore errors */
+       cxl_data_cache_flush(adapter);
+
        /* pcie_warm_reset requests a fundamental pci reset which includes a
         * PERST assert/deassert.  PERST triggers a loading of the image
         * if "user" or "factory" is selected in sysfs */