x86/xen: populate boot_params with EDD data

During early setup of a dom0 kernel, populate boot_params with the
Enhanced Disk Drive (EDD) and MBR signature data.  This makes
information on the BIOS boot device available in /sys/firmware/edd/.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index c8e1c7b95c3b..47d32434d0b6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -31,6 +31,7 @@
 #include <linux/pci.h>
 #include <linux/gfp.h>
 #include <linux/memblock.h>
+#include <linux/edd.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -1306,6 +1307,55 @@ static const struct machine_ops xen_machine_ops __initconst = {
         .emergency_restart = xen_emergency_restart,
 };
 
+static void __init xen_boot_params_init_edd(void)
+{
+#if IS_ENABLED(CONFIG_EDD)
+        struct xen_platform_op op;
+        struct edd_info *edd_info;
+        u32 *mbr_signature;
+        unsigned nr;
+        int ret;
+
+        edd_info = boot_params.eddbuf;
+        mbr_signature = boot_params.edd_mbr_sig_buffer;
+
+        op.cmd = XENPF_firmware_info;
+
+        op.u.firmware_info.type = XEN_FW_DISK_INFO;
+        for (nr = 0; nr < EDDMAXNR; nr++) {
+                struct edd_info *info = edd_info + nr;
+
+                op.u.firmware_info.index = nr;
+                info->params.length = sizeof(info->params);
+                set_xen_guest_handle(op.u.firmware_info.u.disk_info.edd_params,
+                                     &info->params);
+                ret = HYPERVISOR_dom0_op(&op);
+                if (ret)
+                        break;
+
+#define C(x) info->x = op.u.firmware_info.u.disk_info.x
+                C(device);
+                C(version);
+                C(interface_support);
+                C(legacy_max_cylinder);
+                C(legacy_max_head);
+                C(legacy_sectors_per_track);
+#undef C
+        }
+        boot_params.eddbuf_entries = nr;
+
+        op.u.firmware_info.type = XEN_FW_DISK_MBR_SIGNATURE;
+        for (nr = 0; nr < EDD_MBR_SIG_MAX; nr++) {
+                op.u.firmware_info.index = nr;
+                ret = HYPERVISOR_dom0_op(&op);
+                if (ret)
+                        break;
+                mbr_signature[nr] = op.u.firmware_info.u.disk_mbr_signature.mbr_signature;
+        }
+        boot_params.edd_mbr_sig_buf_entries = nr;
+#endif
+}
+
 /*
  * Set up the GDT and segment registers for -fstack-protector.  Until
  * we do this, we have to be careful not to call any stack-protected
@@ -1508,6 +1558,8 @@ asmlinkage void __init xen_start_kernel(void)
                 /* Avoid searching for BIOS MP tables */
                 x86_init.mpparse.find_smp_config = x86_init_noop;
                 x86_init.mpparse.get_smp_config = x86_init_uint_noop;
+
+                xen_boot_params_init_edd();
         }
 #ifdef CONFIG_PCI
         /* PCI BIOS service won't work from a PV guest. */