[Qemu-devel] [PATCH 2/2] Get system state configuration from QEMU and patcth DSDT with it.

[Gleb Natapov <gleb@redhat.com>]

QEMU may want to disable guest's S3/S4 support and it wants to distinguish
between regular powerdown and S4 powerdown. To support that new fw_cfg
option was added that passes supported system states and what value should
guest use to enter each state. States are passed in 6 byte array. Each
byte represents one system state. If byte at offset X has its MSB set
it means that system state X is supported and to enter it guest should
use the value from lowest 7 bits. Patch also detects old QEMU and uses
values that work in backwards compatible way there.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
---
 src/acpi-dsdt.dsl |    7 +++++--
 src/acpi-dsdt.hex |   21 ++++++++++++++++-----
 src/acpi.c        |   12 +++++++++++-
 src/paravirt.c    |   16 ++++++++++++++++
 src/paravirt.h    |    2 ++
 5 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/src/acpi-dsdt.dsl b/src/acpi-dsdt.dsl
index 4bdc268..cd4ce52 100644
--- a/src/acpi-dsdt.dsl
+++ b/src/acpi-dsdt.dsl
@@ -613,6 +613,7 @@ DefinitionBlock (
      * S3 (suspend-to-ram), S4 (suspend-to-disk) and S5 (power-off) type codes:
      * must match piix4 emulation.
      */
+    ACPI_EXTRACT_NAME_STRING acpi_s3_name
     Name (\_S3, Package (0x04)
     {
         0x01,  /* PM1a_CNT.SLP_TYP */
@@ -620,10 +621,12 @@ DefinitionBlock (
         Zero,  /* reserved */
         Zero   /* reserved */
     })
+    ACPI_EXTRACT_NAME_STRING acpi_s4_name
+    ACPI_EXTRACT_PKG_START acpi_s4_pkg
     Name (\_S4, Package (0x04)
     {
-        Zero,  /* PM1a_CNT.SLP_TYP */
-        Zero,  /* PM1b_CNT.SLP_TYP */
+        0x2,  /* PM1a_CNT.SLP_TYP */
+        0x2,  /* PM1b_CNT.SLP_TYP */
         Zero,  /* reserved */
         Zero   /* reserved */
     })
diff --git a/src/acpi-dsdt.hex b/src/acpi-dsdt.hex
index a4af597..8a50f55 100644
--- a/src/acpi-dsdt.hex
+++ b/src/acpi-dsdt.hex
@@ -1,14 +1,20 @@
+static unsigned short acpi_s3_name[] = {
+0xf57
+};
+static unsigned short acpi_s4_name[] = {
+0xf63
+};
 static unsigned char AmlCode[] = {
 0x44,
 0x53,
 0x44,
 0x54,
-0x21,
+0x23,
 0x11,
 0x0,
 0x0,
 0x1,
-0xe8,
+0xcc,
 0x42,
 0x58,
 0x50,
@@ -3943,10 +3949,12 @@ static unsigned char AmlCode[] = {
 0x34,
 0x5f,
 0x12,
-0x6,
+0x8,
 0x4,
-0x0,
-0x0,
+0xa,
+0x2,
+0xa,
+0x2,
 0x0,
 0x0,
 0x8,
@@ -4385,3 +4393,6 @@ static unsigned char AmlCode[] = {
 0xa4,
 0x1
 };
+static unsigned short acpi_s4_pkg[] = {
+0xf6a
+};
diff --git a/src/acpi.c b/src/acpi.c
index 30888b9..1e7d466 100644
--- a/src/acpi.c
+++ b/src/acpi.c
@@ -734,13 +734,23 @@ acpi_bios_init(void)
     }
     if (fadt && !fadt->dsdt) {
         /* default DSDT */
-        void *dsdt = malloc_high(sizeof(AmlCode));
+        char *dsdt = malloc_high(sizeof(AmlCode));
+        char sys_states[6];
         if (!dsdt) {
             warn_noalloc();
             return;
         }
         memcpy(dsdt, AmlCode, sizeof(AmlCode));
         fill_dsdt(fadt, dsdt);
+        qemu_cfg_system_states(sys_states);
+        if (!(sys_states[3] & 128))
+            dsdt[acpi_s3_name[0]] = 'X';
+        if (!(sys_states[4] & 128))
+            dsdt[acpi_s4_name[0]] = 'X';
+        else
+            dsdt[acpi_s4_pkg[0] + 1] = dsdt[acpi_s4_pkg[0] + 3] = sys_states[4] & 127;
+	((struct acpi_table_header*)dsdt)->checksum = 0;
+	((struct acpi_table_header*)dsdt)->checksum -= checksum(dsdt, sizeof(AmlCode));
     }
 
     // Build final rsdt table
diff --git a/src/paravirt.c b/src/paravirt.c
index 9cf77de..201bbc3 100644
--- a/src/paravirt.c
+++ b/src/paravirt.c
@@ -92,6 +92,22 @@ int qemu_cfg_irq0_override(void)
     return v;
 }
 
+int qemu_cfg_system_states(char *states)
+{
+    char s[6] = {128, 0, 0, 129, 128, 128};
+
+    if (qemu_cfg_present) {
+        qemu_cfg_read_entry(states, QEMU_CFG_SYSTEM_STATES, 6);
+        if (states[0])
+            return 1;
+    }
+
+    /* use defaults matching old QEMU */
+    memcpy(states, s, sizeof(s));
+
+    return 0;
+}
+
 u16 qemu_cfg_acpi_additional_tables(void)
 {
     u16 cnt;
diff --git a/src/paravirt.h b/src/paravirt.h
index f39e226..b69646c 100644
--- a/src/paravirt.h
+++ b/src/paravirt.h
@@ -40,6 +40,7 @@ static inline int kvm_para_available(void)
 #define QEMU_CFG_SMBIOS_ENTRIES         (QEMU_CFG_ARCH_LOCAL + 1)
 #define QEMU_CFG_IRQ0_OVERRIDE          (QEMU_CFG_ARCH_LOCAL + 2)
 #define QEMU_CFG_E820_TABLE             (QEMU_CFG_ARCH_LOCAL + 3)
+#define QEMU_CFG_SYSTEM_STATES          (QEMU_CFG_ARCH_LOCAL + 5)
 
 extern int qemu_cfg_present;
 
@@ -109,4 +110,5 @@ u64 romfile_loadint(const char *name, u64 defval);
 u32 qemu_cfg_e820_entries(void);
 void* qemu_cfg_e820_load_next(void *addr);
 
+int qemu_cfg_system_states(char *states);
 #endif
-- 
1.7.7.3