[PATCH v4 02/23] x86/numa: Add 'nohmat' option

[Dan Williams <dan.j.williams@xxxxxxxxx>]

Disable parsing of the HMAT for debug, to workaround broken platform
instances, or cases where it is otherwise not wanted.

Cc: x86@xxxxxxxxxx
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
 Documentation/x86/x86_64/boot-options.rst |    4 ++++
 arch/x86/mm/numa.c                        |    2 ++
 drivers/acpi/numa/hmat.c                  |    8 +++++++-
 include/acpi/acpi_numa.h                  |    8 ++++++++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/Documentation/x86/x86_64/boot-options.rst b/Documentation/x86/x86_64/boot-options.rst
index 2b98efb5ba7f..324cefff92e7 100644
--- a/Documentation/x86/x86_64/boot-options.rst
+++ b/Documentation/x86/x86_64/boot-options.rst
@@ -173,6 +173,10 @@ NUMA
   numa=noacpi
     Don't parse the SRAT table for NUMA setup
 
+  numa=nohmat
+    Don't parse the HMAT table for NUMA setup, or soft-reserved memory
+    partitioning.
+
   numa=fake=<size>[MG]
     If given as a memory unit, fills all system RAM with nodes of
     size interleaved over physical nodes.
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 87c52822cc44..f3805bbaa784 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -41,6 +41,8 @@ static __init int numa_setup(char *opt)
 		return numa_emu_cmdline(opt + 5);
 	if (!strncmp(opt, "noacpi", 6))
 		disable_srat();
+	if (!strncmp(opt, "nohmat", 6))
+		disable_hmat();
 	return 0;
 }
 early_param("numa", numa_setup);
diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
index 2c32cfb72370..a12e36a12618 100644
--- a/drivers/acpi/numa/hmat.c
+++ b/drivers/acpi/numa/hmat.c
@@ -26,6 +26,12 @@
 #include <linux/sysfs.h>
 
 static u8 hmat_revision;
+static int hmat_disable __initdata;
+
+void __init disable_hmat(void)
+{
+	hmat_disable = 1;
+}
 
 static LIST_HEAD(targets);
 static LIST_HEAD(initiators);
@@ -814,7 +820,7 @@ static __init int hmat_init(void)
 	enum acpi_hmat_type i;
 	acpi_status status;
 
-	if (srat_disabled())
+	if (srat_disabled() || hmat_disable)
 		return 0;
 
 	status = acpi_get_table(ACPI_SIG_SRAT, 0, &tbl);
diff --git a/include/acpi/acpi_numa.h b/include/acpi/acpi_numa.h
index 8784183b2204..0e9302285f14 100644
--- a/include/acpi/acpi_numa.h
+++ b/include/acpi/acpi_numa.h
@@ -27,4 +27,12 @@ static inline void disable_srat(void)
 {
 }
 #endif				/* CONFIG_ACPI_NUMA */
+
+#ifdef CONFIG_ACPI_HMAT
+extern void disable_hmat(void);
+#else				/* CONFIG_ACPI_HMAT */
+static inline void disable_hmat(void)
+{
+}
+#endif				/* CONFIG_ACPI_HMAT */
 #endif				/* __ACP_NUMA_H */