tools: Mark ACPI SDTs as NVS in the PVH build path

Commit cefeffc7e583 marked ACPI tables as NVS in the hvmloader path
because SeaBIOS may otherwise just mark it as RAM. There is, however,
yet another reason to do it even in the PVH path. Xen's incarnation of
AML relies on having access to some ACPI tables (e.g: _STA of Processor
objects relies on reading the processor online bit in its MADT entry)

This is problematic if the OS tries to reclaim ACPI memory for page
tables as it's needed for runtime and can't be reclaimed after the OSPM
is up and running.

Fixes: de6d188a519f ("hvmloader: flip "ACPI data" to "ACPI NVS" type for ACPI table region)"
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

diff --git a/tools/firmware/hvmloader/e820.c b/tools/firmware/hvmloader/e820.c
index c490a0bc790c1e70912411f9b1cdf09e661dada2..86d39544e8874fa5915e6ca5467c0e0dc8e2eee8 100644 (file)
--- a/tools/firmware/hvmloader/e820.c
+++ b/tools/firmware/hvmloader/e820.c
@@ -210,6 +210,10 @@ int build_e820_table(struct e820entry *e820,
      * space reuse by an ACPI unaware / buggy bootloader, option ROM, etc.
      * before an ACPI OS takes control. This is possible due to the fact that
      * ACPI NVS memory is explicitly described as non-reclaimable in ACPI spec.
+     *
+     * Furthermore, Xen relies on accessing ACPI tables from within the AML
+     * code exposed to guests. So Xen's ACPI tables are not, in general,
+     * reclaimable.
      */
 
     if ( acpi_enabled )

diff --git a/tools/libs/light/libxl_x86.c b/tools/libs/light/libxl_x86.c
index 0a7f64ad460544d39606153e23778aeec96748f0..0b1c2d3a96f831e1f567808c99acfb09dceb6359 100644 (file)
--- a/tools/libs/light/libxl_x86.c
+++ b/tools/libs/light/libxl_x86.c
@@ -737,12 +737,22 @@ static int domain_construct_memmap(libxl__gc *gc,
         nr++;
     }
 
+    /*
+     * Mark populated reserved memory that contains ACPI tables as ACPI NVS.
+     * That should help the guest to treat it correctly later: e.g. pass to
+     * the next kernel on kexec.
+     *
+     * Furthermore, Xen relies on accessing ACPI tables from within the AML
+     * code exposed to guests. So Xen's ACPI tables are not, in general,
+     * reclaimable.
+     */
+
     for (i = 0; i < MAX_ACPI_MODULES; i++) {
         if (dom->acpi_modules[i].length) {
             e820[nr].addr = dom->acpi_modules[i].guest_addr_out & ~(page_size - 1);
             e820[nr].size = dom->acpi_modules[i].length +
                 (dom->acpi_modules[i].guest_addr_out & (page_size - 1));
-            e820[nr].type = E820_ACPI;
+            e820[nr].type = E820_NVS;
             nr++;
         }
     }