[Xen-devel] [RFC XEN PATCH 06/16] tools: reserve guest memory for ACPI from device model

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

One guest page is reserved for the device model to place guest ACPI. The
base address and size of the reserved area are passed to the device
model via XenStore keys hvmloader/dm-acpi/{address, length}.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxc/include/xc_dom.h            |  1 +
 tools/libxc/xc_dom_x86.c                |  7 +++++++
 tools/libxl/libxl_dom.c                 | 25 +++++++++++++++++++++++++
 xen/include/public/hvm/hvm_xs_strings.h | 11 +++++++++++
 4 files changed, 44 insertions(+)

diff --git a/tools/libxc/include/xc_dom.h b/tools/libxc/include/xc_dom.h
index 608cbc2..19d65cd 100644
--- a/tools/libxc/include/xc_dom.h
+++ b/tools/libxc/include/xc_dom.h
@@ -98,6 +98,7 @@ struct xc_dom_image {
     xen_pfn_t xenstore_pfn;
     xen_pfn_t shared_info_pfn;
     xen_pfn_t bootstack_pfn;
+    xen_pfn_t dm_acpi_pfn;
     xen_pfn_t pfn_alloc_end;
     xen_vaddr_t virt_alloc_end;
     xen_vaddr_t bsd_symtab_start;
diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index 0eab8a7..47f14a1 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -674,6 +674,13 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
                          ioreq_server_pfn(0));
         xc_hvm_param_set(xch, domid, HVM_PARAM_NR_IOREQ_SERVER_PAGES,
                          NR_IOREQ_SERVER_PAGES);
+
+        dom->dm_acpi_pfn = xc_dom_alloc_page(dom, "DM ACPI");
+        if ( dom->dm_acpi_pfn == INVALID_PFN )
+        {
+            DOMPRINTF("Could not allocate page for device model ACPI.");
+            goto error_out;
+        }
     }
 
     rc = xc_dom_alloc_segment(dom, &dom->start_info_seg,
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index d519c8d..f0a1d97 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -865,6 +865,31 @@ static int hvm_build_set_xs_values(libxl__gc *gc,
             goto err;
     }
 
+    if (dom->dm_acpi_pfn) {
+        uint64_t guest_addr_out = dom->dm_acpi_pfn * XC_DOM_PAGE_SIZE(dom);
+
+        if (guest_addr_out >= 0x100000000ULL) {
+            LOG(ERROR,
+                "Guest address of DM ACPI is 0x%"PRIx64", but expected below 
4G",
+                guest_addr_out);
+            goto err;
+        }
+
+        path = GCSPRINTF("/local/domain/%d/"HVM_XS_DM_ACPI_ADDRESS, domid);
+
+        ret = libxl__xs_printf(gc, XBT_NULL, path, "0x%"PRIx64,
+                               guest_addr_out);
+        if (ret)
+            goto err;
+
+        path = GCSPRINTF("/local/domain/%d/"HVM_XS_DM_ACPI_LENGTH, domid);
+
+        ret = libxl__xs_printf(gc, XBT_NULL, path, "0x%"PRIx64,
+                               (uint64_t) XC_DOM_PAGE_SIZE(dom));
+        if (ret)
+            goto err;
+    }
+
     return 0;
 
 err:
diff --git a/xen/include/public/hvm/hvm_xs_strings.h 
b/xen/include/public/hvm/hvm_xs_strings.h
index 146b0b0..f44f71f 100644
--- a/xen/include/public/hvm/hvm_xs_strings.h
+++ b/xen/include/public/hvm/hvm_xs_strings.h
@@ -79,4 +79,15 @@
  */
 #define HVM_XS_OEM_STRINGS             "bios-strings/oem-%d"
 
+/* Follows are XenStore keys for DM ACPI (ACPI built by device model,
+ * e.g. QEMU).
+ *
+ * A reserved area of guest physical memory is used to pass DM
+ * ACPI. Values of following two keys specify the base address and
+ * length (in bytes) of the reserved area.
+ */
+#define HVM_XS_DM_ACPI_ROOT              "hvmloader/dm-acpi"
+#define HVM_XS_DM_ACPI_ADDRESS           HVM_XS_DM_ACPI_ROOT"/address"
+#define HVM_XS_DM_ACPI_LENGTH            HVM_XS_DM_ACPI_ROOT"/length"
+
 #endif /* __XEN_PUBLIC_HVM_HVM_XS_STRINGS_H__ */
-- 
2.10.1


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