[PATCH 08/15] x86/PVH: split pvh_setup_acpi()

[Jan Beulich <jbeulich@xxxxxxxx>]

All E820 manipulations want to happen before the initrd is placed, or else
pvh_steal_ram() may steal from the tail part of it. As a second step,
split placing ACPI data from actually populating it. To reuse size
calculations and limit churn, convert pvh_setup_acpi_{madt,xsdt}() to
two-pass functions: The 1st pass merely reserves space, while the 2nd pass
actually populates information.

While altering the copying of the RSDP pointer into Dom0's start-info, add
a BUILD_BUG_ON() making sure field sizes actually match up.

Fixes: 1d74282c455f ("x86: setup PVHv2 Dom0 ACPI tables")
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -920,8 +920,9 @@ static int __init pvh_setup_acpi_madt(st
     int rc;
 
     /* Count number of interrupt overrides in the MADT. */
-    acpi_table_parse_madt(ACPI_MADT_TYPE_INTERRUPT_OVERRIDE,
-                          acpi_count_intr_ovr, UINT_MAX);
+    if ( !*addr )
+        acpi_table_parse_madt(ACPI_MADT_TYPE_INTERRUPT_OVERRIDE,
+                              acpi_count_intr_ovr, UINT_MAX);
 
     /* Calculate the size of the crafted MADT. */
     size = sizeof(*madt);
@@ -929,6 +930,22 @@ static int __init pvh_setup_acpi_madt(st
     size += sizeof(*intsrcovr) * acpi_intr_overrides;
     size += sizeof(*x2apic) * d->max_vcpus;
 
+    if ( !*addr )
+    {
+        /* Reserve space to place the new MADT in guest memory space. */
+        if ( pvh_steal_ram(d, size, 0, GB(4), addr) )
+        {
+            printk("Unable to steal guest RAM for MADT\n");
+            return -ENOMEM;
+        }
+
+        /* Mark this region as E820_ACPI. */
+        if ( pvh_add_mem_range(d, *addr, *addr + size, E820_ACPI) )
+            printk("Unable to add MADT region to memory map\n");
+
+        return 0;
+    }
+
     madt = xzalloc_bytes(size);
     if ( !madt )
     {
@@ -991,17 +1008,6 @@ static int __init pvh_setup_acpi_madt(st
     madt->header.checksum -= acpi_tb_checksum(ACPI_CAST_PTR(u8, madt), size);
 
     /* Place the new MADT in guest memory space. */
-    if ( pvh_steal_ram(d, size, 0, GB(4), addr) )
-    {
-        printk("Unable to steal guest RAM for MADT\n");
-        rc = -ENOMEM;
-        goto out;
-    }
-
-    /* Mark this region as E820_ACPI. */
-    if ( pvh_add_mem_range(d, *addr, *addr + size, E820_ACPI) )
-        printk("Unable to add MADT region to memory map\n");
-
     rc = hvm_copy_to_guest_phys(*addr, madt, size, d->vcpu[0]);
     if ( rc )
     {
@@ -1116,6 +1122,22 @@ static int __init pvh_setup_acpi_xsdt(st
      */
     size += num_tables * sizeof(xsdt->table_offset_entry[0]);
 
+    if ( !*addr )
+    {
+        /* Reserve space to place the new XSDT in guest memory space. */
+        if ( pvh_steal_ram(d, size, 0, GB(4), addr) )
+        {
+            printk("Unable to find guest RAM for XSDT\n");
+            return -ENOMEM;
+        }
+
+        /* Mark this region as E820_ACPI. */
+        if ( pvh_add_mem_range(d, *addr, *addr + size, E820_ACPI) )
+            printk("Unable to add XSDT region to memory map\n");
+
+        return 0;
+    }
+
     xsdt = xzalloc_bytes(size);
     if ( !xsdt )
     {
@@ -1179,17 +1201,6 @@ static int __init pvh_setup_acpi_xsdt(st
     xsdt->header.checksum -= acpi_tb_checksum(ACPI_CAST_PTR(u8, xsdt), size);
 
     /* Place the new XSDT in guest memory space. */
-    if ( pvh_steal_ram(d, size, 0, GB(4), addr) )
-    {
-        printk("Unable to find guest RAM for XSDT\n");
-        rc = -ENOMEM;
-        goto out;
-    }
-
-    /* Mark this region as E820_ACPI. */
-    if ( pvh_add_mem_range(d, *addr, *addr + size, E820_ACPI) )
-        printk("Unable to add XSDT region to memory map\n");
-
     rc = hvm_copy_to_guest_phys(*addr, xsdt, size, d->vcpu[0]);
     if ( rc )
     {
@@ -1205,18 +1216,18 @@ static int __init pvh_setup_acpi_xsdt(st
     return rc;
 }
 
-static int __init pvh_setup_acpi(struct domain *d, paddr_t start_info)
+struct acpi_info {
+    paddr_t madt;
+    paddr_t xsdt;
+    paddr_t rsdp;
+};
+
+static int __init pvh_place_acpi(
+    struct domain *d,
+    struct acpi_info *info)
 {
-    unsigned long pfn, nr_pages;
-    paddr_t madt_paddr, xsdt_paddr, rsdp_paddr;
     unsigned int i;
     int rc;
-    struct acpi_table_rsdp *native_rsdp, rsdp = {
-        .signature = ACPI_SIG_RSDP,
-        .revision = 2,
-        .length = sizeof(rsdp),
-    };
-
 
     /* Scan top-level tables and add their regions to the guest memory map. */
     for( i = 0; i < acpi_gbl_root_table_list.count; i++ )
@@ -1239,6 +1250,8 @@ static int __init pvh_setup_acpi(struct
     /* Identity map ACPI e820 regions. */
     for ( i = 0; i < d->arch.nr_e820; i++ )
     {
+        unsigned long pfn, nr_pages;
+
         if ( d->arch.e820[i].type != E820_ACPI &&
              d->arch.e820[i].type != E820_NVS )
             continue;
@@ -1267,32 +1280,49 @@ static int __init pvh_setup_acpi(struct
         }
     }
 
-    rc = pvh_setup_acpi_madt(d, &madt_paddr);
+    rc = pvh_setup_acpi_madt(d, &info->madt);
     if ( rc )
         return rc;
 
-    rc = pvh_setup_acpi_xsdt(d, madt_paddr, &xsdt_paddr);
+    rc = pvh_setup_acpi_xsdt(d, info->madt, &info->xsdt);
     if ( rc )
         return rc;
 
-    /* Craft a custom RSDP. */
-    native_rsdp = acpi_os_map_memory(acpi_os_get_root_pointer(), sizeof(rsdp));
-    if ( !native_rsdp )
+    if ( pvh_steal_ram(d, sizeof(struct acpi_table_rsdp), 0, GB(4),
+                       &info->rsdp) )
     {
-        printk("Failed to map native RSDP\n");
+        printk("Unable to allocate guest RAM for RSDP\n");
         return -ENOMEM;
     }
-    memcpy(rsdp.oem_id, native_rsdp->oem_id, sizeof(rsdp.oem_id));
-    acpi_os_unmap_memory(native_rsdp, sizeof(rsdp));
-    rsdp.xsdt_physical_address = xsdt_paddr;
-    /*
-     * Calling acpi_tb_checksum here is a layering violation, but
-     * introducing a wrapper for such simple usage seems overkill.
-     */
-    rsdp.checksum -= acpi_tb_checksum(ACPI_CAST_PTR(u8, &rsdp),
-                                      ACPI_RSDP_REV0_SIZE);
-    rsdp.extended_checksum -= acpi_tb_checksum(ACPI_CAST_PTR(u8, &rsdp),
-                                               sizeof(rsdp));
+
+    /* Mark this region as E820_ACPI. */
+    if ( pvh_add_mem_range(d, info->rsdp,
+                           info->rsdp + sizeof(struct acpi_table_rsdp),
+                           E820_ACPI) )
+        printk("Unable to add RSDP region to memory map\n");
+
+    return 0;
+}
+
+static int __init pvh_setup_acpi(
+    struct domain *d,
+    struct acpi_info *info,
+    paddr_t start_info)
+{
+    int rc;
+    struct acpi_table_rsdp *native_rsdp, rsdp = {
+        .signature = ACPI_SIG_RSDP,
+        .revision = 2,
+        .length = sizeof(rsdp),
+    };
+
+    rc = pvh_setup_acpi_madt(d, &info->madt);
+    if ( rc )
+        return rc;
+
+    rc = pvh_setup_acpi_xsdt(d, info->madt, &info->xsdt);
+    if ( rc )
+        return rc;
 
     /*
      * Place the new RSDP in guest memory space.
@@ -1302,19 +1332,27 @@ static int __init pvh_setup_acpi(struct
      * the native RSDT, and should not be used for the Dom0 kernel's boot
      * purposes (we keep it visible for post boot access).
      */
-    if ( pvh_steal_ram(d, sizeof(rsdp), 0, GB(4), &rsdp_paddr) )
+    native_rsdp = acpi_os_map_memory(acpi_os_get_root_pointer(), sizeof(rsdp));
+    if ( !native_rsdp )
     {
-        printk("Unable to allocate guest RAM for RSDP\n");
+        printk("Failed to map native RSDP\n");
         return -ENOMEM;
     }
+    memcpy(rsdp.oem_id, native_rsdp->oem_id, sizeof(rsdp.oem_id));
+    acpi_os_unmap_memory(native_rsdp, sizeof(rsdp));
+    rsdp.xsdt_physical_address = info->xsdt;
 
-    /* Mark this region as E820_ACPI. */
-    if ( pvh_add_mem_range(d, rsdp_paddr, rsdp_paddr + sizeof(rsdp),
-                           E820_ACPI) )
-        printk("Unable to add RSDP region to memory map\n");
+    /*
+     * Calling acpi_tb_checksum here is a layering violation, but
+     * introducing a wrapper for such simple usage seems overkill.
+     */
+    rsdp.checksum -= acpi_tb_checksum(ACPI_CAST_PTR(u8, &rsdp),
+                                      ACPI_RSDP_REV0_SIZE);
+    rsdp.extended_checksum -= acpi_tb_checksum(ACPI_CAST_PTR(u8, &rsdp),
+                                               sizeof(rsdp));
 
     /* Copy RSDP into guest memory. */
-    rc = hvm_copy_to_guest_phys(rsdp_paddr, &rsdp, sizeof(rsdp), d->vcpu[0]);
+    rc = hvm_copy_to_guest_phys(info->rsdp, &rsdp, sizeof(rsdp), d->vcpu[0]);
     if ( rc )
     {
         printk("Unable to copy RSDP into guest memory\n");
@@ -1322,9 +1360,11 @@ static int __init pvh_setup_acpi(struct
     }
 
     /* Copy RSDP address to start_info. */
+    BUILD_BUG_ON(sizeof(info->rsdp) !=
+                 sizeof_field(struct hvm_start_info, rsdp_paddr));
     rc = hvm_copy_to_guest_phys(start_info +
                                 offsetof(struct hvm_start_info, rsdp_paddr),
-                                &rsdp_paddr,
+                                &info->rsdp,
                                 sizeof_field(struct hvm_start_info, 
rsdp_paddr),
                                 d->vcpu[0]);
     if ( rc )
@@ -1361,6 +1401,7 @@ int __init dom0_construct_pvh(const stru
     struct elf_binary elf;
     struct e820entry *orig_e820;
     unsigned int nr_orig_e820;
+    struct acpi_info acpi = {};
     int rc;
 
     printk(XENLOG_INFO "*** Building a PVH Dom%d ***\n", d->domain_id);
@@ -1414,6 +1455,13 @@ int __init dom0_construct_pvh(const stru
         return rc;
     }
 
+    rc = pvh_place_acpi(d, &acpi);
+    if ( rc )
+    {
+        printk("Failed to place Dom0 ACPI tables: %d\n", rc);
+        return rc;
+    }
+
     rc = pvh_populate_p2m(d, orig_e820, nr_orig_e820);
     if ( rc )
     {
@@ -1437,7 +1485,7 @@ int __init dom0_construct_pvh(const stru
         return rc;
     }
 
-    rc = pvh_setup_acpi(d, start_info);
+    rc = pvh_setup_acpi(d, &acpi, start_info);
     if ( rc )
     {
         printk("Failed to setup Dom0 ACPI tables: %d\n", rc);