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authorHuang Rui <ray.huang@amd.com>2015-08-10 12:19:53 +0200
committerIngo Molnar <mingo@kernel.org>2015-08-22 14:52:16 +0200
commitf96756746c7909de37db3d03ac5fd5cfb2757f38 (patch)
tree45032ea51d40f96f21b0e1c534b0c360eb01dee4 /arch/x86/include/asm
parentf0a97af83f6287357dcc100c859ec0066f164f32 (diff)
x86/asm: Add MONITORX/MWAITX instruction support
AMD Carrizo processors (Family 15h, Models 60h-6fh) added a new feature called MWAITX (MWAIT with extensions) as an extension to MONITOR/MWAIT. This new instruction controls a configurable timer which causes the core to exit wait state on timer expiration, in addition to "normal" MWAIT condition of reading from a monitored VA. Compared to MONITOR/MWAIT, there are minor differences in opcode and input parameters: MWAITX ECX[1]: enable timer if set MWAITX EBX[31:0]: max wait time expressed in SW P0 clocks == TSC. The software P0 frequency is the same as the TSC frequency. MWAIT MWAITX opcode 0f 01 c9 | 0f 01 fb ECX[0] value of RFLAGS.IF seen by instruction ECX[1] unused/#GP if set | enable timer if set ECX[31:2] unused/#GP if set EAX unused (reserve for hint) EBX[31:0] unused | max wait time (SW P0 == TSC) MONITOR MONITORX opcode 0f 01 c8 | 0f 01 fa EAX (logical) address to monitor ECX #GP if not zero Max timeout = EBX/(TSC frequency) Signed-off-by: Huang Rui <ray.huang@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Aaron Lu <aaron.lu@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andreas Herrmann <herrmann.der.user@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dirk Brandewie <dirk.j.brandewie@intel.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Frédéric Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <bitbucket@online.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Li <tony.li@amd.com> Link: http://lkml.kernel.org/r/1439201994-28067-3-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm')
-rw-r--r--arch/x86/include/asm/cpufeature.h1
-rw-r--r--arch/x86/include/asm/mwait.h45
2 files changed, 46 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 3d6606fb97d0..a39e5708209b 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -176,6 +176,7 @@
#define X86_FEATURE_PERFCTR_NB ( 6*32+24) /* NB performance counter extensions */
#define X86_FEATURE_BPEXT (6*32+26) /* data breakpoint extension */
#define X86_FEATURE_PERFCTR_L2 ( 6*32+28) /* L2 performance counter extensions */
+#define X86_FEATURE_MWAITX ( 6*32+29) /* MWAIT extension (MONITORX/MWAITX) */
/*
* Auxiliary flags: Linux defined - For features scattered in various
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index 653dfa7662e1..c70689b5e5aa 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -14,6 +14,9 @@
#define CPUID5_ECX_INTERRUPT_BREAK 0x2
#define MWAIT_ECX_INTERRUPT_BREAK 0x1
+#define MWAITX_ECX_TIMER_ENABLE BIT(1)
+#define MWAITX_MAX_LOOPS ((u32)-1)
+#define MWAITX_DISABLE_CSTATES 0xf
static inline void __monitor(const void *eax, unsigned long ecx,
unsigned long edx)
@@ -23,6 +26,14 @@ static inline void __monitor(const void *eax, unsigned long ecx,
:: "a" (eax), "c" (ecx), "d"(edx));
}
+static inline void __monitorx(const void *eax, unsigned long ecx,
+ unsigned long edx)
+{
+ /* "monitorx %eax, %ecx, %edx;" */
+ asm volatile(".byte 0x0f, 0x01, 0xfa;"
+ :: "a" (eax), "c" (ecx), "d"(edx));
+}
+
static inline void __mwait(unsigned long eax, unsigned long ecx)
{
/* "mwait %eax, %ecx;" */
@@ -30,6 +41,40 @@ static inline void __mwait(unsigned long eax, unsigned long ecx)
:: "a" (eax), "c" (ecx));
}
+/*
+ * MWAITX allows for a timer expiration to get the core out a wait state in
+ * addition to the default MWAIT exit condition of a store appearing at a
+ * monitored virtual address.
+ *
+ * Registers:
+ *
+ * MWAITX ECX[1]: enable timer if set
+ * MWAITX EBX[31:0]: max wait time expressed in SW P0 clocks. The software P0
+ * frequency is the same as the TSC frequency.
+ *
+ * Below is a comparison between MWAIT and MWAITX on AMD processors:
+ *
+ * MWAIT MWAITX
+ * opcode 0f 01 c9 | 0f 01 fb
+ * ECX[0] value of RFLAGS.IF seen by instruction
+ * ECX[1] unused/#GP if set | enable timer if set
+ * ECX[31:2] unused/#GP if set
+ * EAX unused (reserve for hint)
+ * EBX[31:0] unused | max wait time (P0 clocks)
+ *
+ * MONITOR MONITORX
+ * opcode 0f 01 c8 | 0f 01 fa
+ * EAX (logical) address to monitor
+ * ECX #GP if not zero
+ */
+static inline void __mwaitx(unsigned long eax, unsigned long ebx,
+ unsigned long ecx)
+{
+ /* "mwaitx %eax, %ebx, %ecx;" */
+ asm volatile(".byte 0x0f, 0x01, 0xfb;"
+ :: "a" (eax), "b" (ebx), "c" (ecx));
+}
+
static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
{
trace_hardirqs_on();