[Xen-devel] [PATCH] ACPI/APEI: fix ERST MOVE_DATA instruction implementation

["Jan Beulich" <JBeulich@xxxxxxxx>]

The src_base and dst_base fields in apei_exec_context are physical
address, so they should be ioremaped before being used in ERST
MOVE_DATA instruction.

Reported-by: Javier Martinez Canillas <martinez.javier@xxxxxxxxx>
Reported-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx>

Replace use of ioremap() by __acpi_map_table()/set_fixmap(). Fix error
handling.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Note that I have no way to test this code other than by having it go
through the tester, since I have no hardware available to reproduce
the regression found there (in other words, this is just a blind
attempt at addressing the problem uncovered by 26060:4fc87c2f31a0).

--- a/xen/drivers/acpi/apei/erst.c
+++ b/xen/drivers/acpi/apei/erst.c
@@ -247,15 +247,64 @@ static int erst_exec_move_data(struct ap
 {
        int rc;
        u64 offset;
+#ifdef CONFIG_X86
+       enum fixed_addresses idx;
+#endif
+       void *src, *dst;
+
+       /* ioremap does not work in interrupt context */
+       if (in_irq()) {
+               printk(KERN_WARNING
+                      "MOVE_DATA cannot be used in interrupt context\n");
+               return -EBUSY;
+       }
 
        rc = __apei_exec_read_register(entry, &offset);
        if (rc)
                return rc;
-       memmove((void *)(unsigned long)(ctx->dst_base + offset),
-               (void *)(unsigned long)(ctx->src_base + offset),
-               ctx->var2);
 
-       return 0;
+#ifdef CONFIG_X86
+       switch (ctx->var2) {
+       case 0:
+               return 0;
+       case 1 ... PAGE_SIZE:
+               break;
+       default:
+               printk(KERN_WARNING
+                      "MOVE_DATA cannot be used for %#"PRIx64" bytes of 
data\n",
+                      ctx->var2);
+               return -EOPNOTSUPP;
+       }
+
+       src = __acpi_map_table(ctx->src_base + offset, ctx->var2);
+#else
+       src = ioremap(ctx->src_base + offset, ctx->var2);
+#endif
+       if (!src)
+               return -ENOMEM;
+
+#ifdef CONFIG_X86
+       BUILD_BUG_ON(FIX_ACPI_PAGES < 4);
+       idx = virt_to_fix((unsigned long)src + 2 * PAGE_SIZE);
+       offset += ctx->dst_base;
+       dst = (void *)fix_to_virt(idx) + (offset & ~PAGE_MASK);
+       set_fixmap(idx, offset);
+       if (PFN_DOWN(offset) != PFN_DOWN(offset + ctx->var2 - 1)) {
+               idx = virt_to_fix((unsigned long)dst + PAGE_SIZE);
+               set_fixmap(idx, offset + PAGE_SIZE);
+       }
+#else
+       dst = ioremap(ctx->dst_base + offset, ctx->var2);
+#endif
+       if (dst) {
+               memmove(dst, src, ctx->var2);
+               iounmap(dst);
+       } else
+               rc = -ENOMEM;
+
+       iounmap(src);
+
+       return rc;
 }
 
 static struct apei_exec_ins_type erst_ins_type[] = {

Attachment: ACPI-ERST-move-data-map.patch
Description: Text document

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