QEMU e820 reservation patch

Hi,

Kevin and I have agreed on the approach for this one now. So here is
the latest version of the patch for QEMU, submitting e820 reservation
entries via fw_cfg.

Cheers,
Jes

Use qemu-cfg to provide the BIOS with an optional table of e820 entries.

Notify the BIOS of the location of the TSS+EPT range to by reserving
it via the e820 table.

This matches a corresponding patch for Seabios, however older versions
of Seabios will default to the hardcoded address range and stay
compatible with current QEMU.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/pc.c

@@ -59,6 +59,7 @@
 #define FW_CFG_ACPI_TABLES (FW_CFG_ARCH_LOCAL + 0)
 #define FW_CFG_SMBIOS_ENTRIES (FW_CFG_ARCH_LOCAL + 1)
 #define FW_CFG_IRQ0_OVERRIDE (FW_CFG_ARCH_LOCAL + 2)
+#define FW_CFG_E820_TABLE (FW_CFG_ARCH_LOCAL + 3)
 
 #define MAX_IDE_BUS 2
 
@@ -67,6 +68,21 @@ static RTCState *rtc_state;
 static PITState *pit;
 static PCII440FXState *i440fx_state;
 
+#define E820_NR_ENTRIES		16
+
+struct e820_entry {
+    uint64_t address;
+    uint64_t length;
+    uint32_t type;
+};
+
+struct e820_table {
+    uint32_t count;
+    struct e820_entry entry[E820_NR_ENTRIES];
+};
+
+static struct e820_table e820_table;
+
 typedef struct isa_irq_state {
     qemu_irq *i8259;
     qemu_irq *ioapic;
@@ -435,6 +451,23 @@ static void bochs_bios_write(void *opaque, uint32_t addr, uint32_t val)
     }
 }
 
+int e820_add_entry(uint64_t address, uint64_t length, uint32_t type)
+{
+    int index = e820_table.count;
+    struct e820_entry *entry;
+
+    if (index >= E820_NR_ENTRIES)
+        return -EBUSY;
+    entry = &e820_table.entry[index];
+
+    entry->address = address;
+    entry->length = length;
+    entry->type = type;
+
+    e820_table.count++;
+    return e820_table.count;
+}
+
 static void *bochs_bios_init(void)
 {
     void *fw_cfg;
@@ -466,6 +499,8 @@ static void *bochs_bios_init(void)
     if (smbios_table)
         fw_cfg_add_bytes(fw_cfg, FW_CFG_SMBIOS_ENTRIES,
                          smbios_table, smbios_len);
+    fw_cfg_add_bytes(fw_cfg, FW_CFG_E820_TABLE, (uint8_t *)&e820_table,
+                     sizeof(struct e820_table));
 
     /* allocate memory for the NUMA channel: one (64bit) word for the number
      * of nodes, one word for each VCPU->node and one word for each node to

hw/pc.h

@@ -150,4 +150,14 @@ void isa_cirrus_vga_init(void);
 void isa_ne2000_init(int base, int irq, NICInfo *nd);
 
 int cpu_is_bsp(CPUState *env);
+
+/* e820 types */
+#define E820_RAM        1
+#define E820_RESERVED   2
+#define E820_ACPI       3
+#define E820_NVS        4
+#define E820_UNUSABLE   5
+
+int e820_add_entry(uint64_t, uint64_t, uint32_t);
+
 #endif

target-i386/kvm.c

@@ -24,6 +24,7 @@
 #include "cpu.h"
 #include "gdbstub.h"
 #include "host-utils.h"
+#include "hw/pc.h"
 
 #ifdef CONFIG_KVM_PARA
 #include <linux/kvm_para.h>
@@ -362,6 +363,13 @@ int kvm_arch_init(KVMState *s, int smp_cpus)
      * as unavaible memory.  FIXME, need to ensure the e820 map deals with
      * this?
      */
+    /*
+     * Tell fw_cfg to notify the BIOS to reserve the range.
+     */
+    if (e820_add_entry(0xfffbc000, 0x4000, E820_RESERVED) < 0) {
+        perror("e820_add_entry() table is full");
+        exit(1);
+    }
     return kvm_vm_ioctl(s, KVM_SET_TSS_ADDR, 0xfffbd000);
 }