[Xen-devel] [PATCH v4 06/21] arm/acpi: Parse FADT table and get PSCI flags

[Shannon Zhao <zhaoshenglong@xxxxxxxxxx>]

From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>

There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set, the
former signals to the OS that the hardware is PSCI compliant. The latter
selects the appropriate conduit for PSCI calls by toggling between
Hypervisor Calls (HVC) and Secure Monitor Calls (SMC). FADT table
contains such information, parse FADT to get the flags for furture
usage.

Since STAO table and the GIC version are introduced by ACPI 6.0, we will
check the version and only parse FADT table with version >= 6.0. If
firmware provides ACPI tables with ACPI version less than 6.0, OS will
be messed up with those information, so disable ACPI if we get an FADT
table with version less than 6.0.

Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Signed-off-by: Naresh Bhat <naresh.bhat@xxxxxxxxxx>
Signed-off-by: Parth Dixit <parth.dixit@xxxxxxxxxx>
Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
---
V4: drop disable_acpi in acpi_parse_fadt
---
 xen/arch/arm/acpi/boot.c   | 30 ++++++++++++++++++++++++++++++
 xen/arch/arm/acpi/lib.c    | 12 ++++++++++++
 xen/include/asm-arm/acpi.h |  9 +++++++++
 3 files changed, 51 insertions(+)

diff --git a/xen/arch/arm/acpi/boot.c b/xen/arch/arm/acpi/boot.c
index 1570f7e..6b33fbe 100644
--- a/xen/arch/arm/acpi/boot.c
+++ b/xen/arch/arm/acpi/boot.c
@@ -27,9 +27,32 @@
 
 #include <xen/init.h>
 #include <xen/acpi.h>
+#include <xen/errno.h>
+#include <acpi/actables.h>
+#include <xen/mm.h>
 
 #include <asm/acpi.h>
 
+static int __init acpi_parse_fadt(struct acpi_table_header *table)
+{
+    struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
+
+    /*
+     * Revision in table header is the FADT Major revision, and there
+     * is a minor revision of FADT which was introduced by ACPI 6.0,
+     * we only deal with ACPI 6.0 or newer revision to get GIC and SMP
+     * boot protocol configuration data, or we will disable ACPI.
+     */
+    if ( table->revision > 6
+         || (table->revision == 6 && fadt->minor_revision >= 0) )
+        return 0;
+
+    printk("Unsupported FADT revision %d.%d, should be 6.0+, will disable 
ACPI\n",
+            table->revision, fadt->minor_revision);
+
+    return -EINVAL;
+}
+
 /*
  * acpi_boot_table_init() called from setup_arch(), always.
  *      1. find RSDP and get its address, and then find XSDT
@@ -54,5 +77,12 @@ int __init acpi_boot_table_init(void)
         return error;
     }
 
+    if ( acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt) )
+    {
+        /* disable ACPI if no FADT is found */
+        disable_acpi();
+        printk("Can't find FADT\n");
+    }
+
     return 0;
 }
diff --git a/xen/arch/arm/acpi/lib.c b/xen/arch/arm/acpi/lib.c
index f817fe6..a30e4e6 100644
--- a/xen/arch/arm/acpi/lib.c
+++ b/xen/arch/arm/acpi/lib.c
@@ -50,3 +50,15 @@ char *__acpi_map_table(paddr_t phys, unsigned long size)
 
        return ((char *) base + offset);
 }
+
+/* 1 to indicate PSCI 0.2+ is implemented */
+bool_t __init acpi_psci_present(void)
+{
+    return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT;
+}
+
+/* 1 to indicate HVC is present instead of SMC as the PSCI conduit */
+bool_t __init acpi_psci_hvc_present(void)
+{
+    return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC;
+}
diff --git a/xen/include/asm-arm/acpi.h b/xen/include/asm-arm/acpi.h
index 6a037c9..1ce88f8 100644
--- a/xen/include/asm-arm/acpi.h
+++ b/xen/include/asm-arm/acpi.h
@@ -31,6 +31,15 @@
 #define ACPI_MAP_MEM_ATTR          PAGE_HYPERVISOR
 
 extern bool_t acpi_disabled;
+
+#ifdef CONFIG_ACPI
+bool_t __init acpi_psci_present(void);
+bool_t __init acpi_psci_hvc_present(void);
+#else
+static inline bool_t acpi_psci_present(void) { return false; }
+static inline bool_t acpi_psci_hvc_present(void) {return false; }
+#endif /* CONFIG_ACPI */
+
 /* Basic configuration for ACPI */
 static inline void disable_acpi(void)
 {
-- 
2.0.4



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