[Xen-devel] [PATCH] ACPI/ERST: fix table mapping

["Jan Beulich" <JBeulich@xxxxxxxx>]

acpi_get_table(), when executed before reaching SYS_STATE_active, will
return a mapping valid only until the next invocation of that funciton.
Consequently storing the returned pointer for later use is incorrect.
Copy the logic used in VT-d's DMAR handling.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/drivers/acpi/apei/erst.c
+++ b/xen/drivers/acpi/apei/erst.c
@@ -383,6 +383,8 @@ static int erst_get_erange(struct erst_e
        return 0;
 }
 
+#ifndef NDEBUG /* currently dead code */
+
 static ssize_t __erst_get_record_count(void)
 {
        struct apei_exec_context ctx;
@@ -447,6 +449,8 @@ int erst_get_next_record_id(u64 *record_
        return rc;
 }
 
+#endif /* currently dead code */
+
 static int __erst_write_to_storage(u64 offset)
 {
        struct apei_exec_context ctx;
@@ -777,21 +781,27 @@ int __init erst_init(void)
 {
        int rc = 0;
        acpi_status status;
+       acpi_physical_address erst_addr;
+       acpi_native_uint erst_len;
        struct apei_exec_context ctx;
 
        if (acpi_disabled)
                return -ENODEV;
 
-       status = acpi_get_table(ACPI_SIG_ERST, 0,
-                               (struct acpi_table_header **)&erst_tab);
+       status = acpi_get_table_phys(ACPI_SIG_ERST, 0, &erst_addr, &erst_len);
        if (status == AE_NOT_FOUND) {
                printk(KERN_INFO "ERST table was not found\n");
                return -ENODEV;
-       } else if (ACPI_FAILURE(status)) {
+       }
+       if (ACPI_FAILURE(status)) {
                const char *msg = acpi_format_exception(status);
                printk(KERN_WARNING "Failed to get ERST table: %s\n", msg);
                return -EINVAL;
        }
+       map_pages_to_xen((unsigned long)__va(erst_addr), PFN_DOWN(erst_addr),
+                        PFN_UP(erst_addr + erst_len) - PFN_DOWN(erst_addr),
+                        PAGE_HYPERVISOR);
+       erst_tab = __va(erst_addr);
 
        rc = erst_check_table(erst_tab);
        if (rc) {




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