[PATCH 2/2] xen/x86/pvh: copy ACPI tables to Dom0 instead of mapping

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxx>

Mapping the ACPI tables to Dom0 PVH 1:1 leads to memory corruptions of
the tables in the guest. Instead, copy the tables to Dom0.

This is a workaround.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
---
As mentioned in the cover letter, this is a RFC workaround as I don't
know the cause of the underlying problem. I do know that this patch
solves what would be otherwise a hang at boot when Dom0 PVH attempts to
parse ACPI tables.
---
 xen/arch/x86/hvm/dom0_build.c | 107 +++++++++-------------------------
 1 file changed, 27 insertions(+), 80 deletions(-)

diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index 5fde769863..a6037fc6ed 100644
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -73,32 +73,6 @@ static void __init print_order_stats(const struct domain *d)
             printk("order %2u allocations: %u\n", i, order_stats[i]);
 }
 
-static int __init modify_identity_mmio(struct domain *d, unsigned long pfn,
-                                       unsigned long nr_pages, const bool map)
-{
-    int rc;
-
-    for ( ; ; )
-    {
-        rc = map ?   map_mmio_regions(d, _gfn(pfn), nr_pages, _mfn(pfn))
-                 : unmap_mmio_regions(d, _gfn(pfn), nr_pages, _mfn(pfn));
-        if ( rc == 0 )
-            break;
-        if ( rc < 0 )
-        {
-            printk(XENLOG_WARNING
-                   "Failed to identity %smap [%#lx,%#lx) for d%d: %d\n",
-                   map ? "" : "un", pfn, pfn + nr_pages, d->domain_id, rc);
-            break;
-        }
-        nr_pages -= rc;
-        pfn += rc;
-        process_pending_softirqs();
-    }
-
-    return rc;
-}
-
 /* Populate a HVM memory range using the biggest possible order. */
 static int __init pvh_populate_memory_range(struct domain *d,
                                             unsigned long start,
@@ -967,6 +941,8 @@ static int __init pvh_setup_acpi_xsdt(struct domain *d, 
paddr_t madt_addr,
     unsigned long size = sizeof(*xsdt);
     unsigned int i, j, num_tables = 0;
     int rc;
+    struct acpi_table_fadt fadt;
+    unsigned long fadt_addr = 0, dsdt_addr = 0, facs_addr = 0, fadt_size = 0;
     struct acpi_table_header header = {
         .signature    = "XSDT",
         .length       = sizeof(struct acpi_table_header),
@@ -1013,10 +989,33 @@ static int __init pvh_setup_acpi_xsdt(struct domain *d, 
paddr_t madt_addr,
     /* Copy the addresses of the rest of the allowed tables. */
     for( i = 0, j = 1; i < acpi_gbl_root_table_list.count; i++ )
     {
+        void *table;
+
+        pvh_steal_ram(d, tables[i].length, 0, GB(4), addr);
+        table = acpi_os_map_memory(tables[i].address, tables[i].length);
+        hvm_copy_to_guest_phys(*addr, table, tables[i].length, d->vcpu[0]);
+        pvh_add_mem_range(d, *addr, *addr + tables[i].length, E820_ACPI);
+
+        if ( !strncmp(tables[i].signature.ascii, ACPI_SIG_FADT, 
ACPI_NAME_SIZE) )
+        {
+            memcpy(&fadt, table, tables[i].length);
+            fadt_addr = *addr;
+            fadt_size = tables[i].length;
+        }
+        else if ( !strncmp(tables[i].signature.ascii, ACPI_SIG_DSDT, 
ACPI_NAME_SIZE) )
+                dsdt_addr = *addr;
+        else if ( !strncmp(tables[i].signature.ascii, ACPI_SIG_FACS, 
ACPI_NAME_SIZE) )
+                facs_addr = *addr;
+
         if ( pvh_acpi_xsdt_table_allowed(tables[i].signature.ascii,
-                                         tables[i].address, tables[i].length) )
-            xsdt->table_offset_entry[j++] = tables[i].address;
+                    tables[i].address, tables[i].length) )
+            xsdt->table_offset_entry[j++] = *addr;
+
+        acpi_os_unmap_memory(table, tables[i].length);
     }
+    fadt.dsdt = dsdt_addr;
+    fadt.facs = facs_addr;
+    hvm_copy_to_guest_phys(fadt_addr, &fadt, fadt_size, d->vcpu[0]);
 
     xsdt->header.revision = 1;
     xsdt->header.length = size;
@@ -1055,9 +1054,7 @@ static int __init pvh_setup_acpi_xsdt(struct domain *d, 
paddr_t madt_addr,
 
 static int __init pvh_setup_acpi(struct domain *d, paddr_t start_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,
@@ -1065,56 +1062,6 @@ static int __init pvh_setup_acpi(struct domain *d, 
paddr_t start_info)
         .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++ )
-    {
-        const char *sig = acpi_gbl_root_table_list.tables[i].signature.ascii;
-        unsigned long addr = acpi_gbl_root_table_list.tables[i].address;
-        unsigned long size = acpi_gbl_root_table_list.tables[i].length;
-
-        /*
-         * Make sure the original MADT is also mapped, so that Dom0 can
-         * properly access the data returned by _MAT methods in case it's
-         * re-using MADT memory.
-         */
-        if ( strncmp(sig, ACPI_SIG_MADT, ACPI_NAME_SIZE)
-             ? pvh_acpi_table_allowed(sig, addr, size)
-             : !acpi_memory_banned(addr, size) )
-             pvh_add_mem_range(d, addr, addr + size, E820_ACPI);
-    }
-
-    /* Identity map ACPI e820 regions. */
-    for ( i = 0; i < d->arch.nr_e820; i++ )
-    {
-        if ( d->arch.e820[i].type != E820_ACPI &&
-             d->arch.e820[i].type != E820_NVS )
-            continue;
-
-        pfn = PFN_DOWN(d->arch.e820[i].addr);
-        nr_pages = PFN_UP((d->arch.e820[i].addr & ~PAGE_MASK) +
-                          d->arch.e820[i].size);
-
-        /* Memory below 1MB has been dealt with by pvh_populate_p2m(). */
-        if ( pfn < PFN_DOWN(MB(1)) )
-        {
-            if ( pfn + nr_pages <= PFN_DOWN(MB(1)) )
-                continue;
-
-            /* This shouldn't happen, but is easy to deal with. */
-            nr_pages -= PFN_DOWN(MB(1)) - pfn;
-            pfn = PFN_DOWN(MB(1));
-        }
-
-        rc = modify_identity_mmio(d, pfn, nr_pages, true);
-        if ( rc )
-        {
-            printk("Failed to map ACPI region [%#lx, %#lx) into Dom0 memory 
map\n",
-                   pfn, pfn + nr_pages);
-            return rc;
-        }
-    }
-
     rc = pvh_setup_acpi_madt(d, &madt_paddr);
     if ( rc )
         return rc;
-- 
2.25.1