From: Fenghua Yu fenghua.yu@intel.com
mainline inclusion from mainline-v4.20-rc1 commit 33823f4d63f7a010653d219800539409a78ef4be category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I4MKP4 CVE: NA
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MOVDIRI moves doubleword or quadword from register to memory through direct store which is implemented by using write combining (WC) for writing data directly into memory without caching the data.
Programmable agents can handle streaming offload (e.g. high speed packet processing in network). Hardware implements a doorbell (tail pointer) register that is updated by software when adding new work-elements to the streaming offload work-queue.
MOVDIRI can be used as the doorbell write which is a 4-byte or 8-byte uncachable write to MMIO. MOVDIRI has lower overhead than other ways to write the doorbell.
Availability of the MOVDIRI instruction is indicated by the presence of the CPUID feature flag MOVDIRI(CPUID.0x07.0x0:ECX[bit 27]).
Please check the latest Intel Architecture Instruction Set Extensions and Future Features Programming Reference for more details on the CPUID feature MOVDIRI flag.
Signed-off-by: Fenghua Yu fenghua.yu@intel.com Cc: Andy Lutomirski luto@amacapital.net Cc: Ashok Raj ashok.raj@intel.com Cc: Borislav Petkov bp@alien8.de Cc: Brian Gerst brgerst@gmail.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: H. Peter Anvin hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Ravi V Shankar ravi.v.shankar@intel.com Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/1540418237-125817-2-git-send-email-fenghua.yu@intel... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Jackie Liu liuyun01@kylinos.cn Signed-off-by: Laibin Qiu qiulaibin@huawei.com --- arch/x86/include/asm/cpufeatures.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index b40125de2770..35ff9c7168c9 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -363,6 +363,7 @@ #define X86_FEATURE_LA57 (16*32+16) /* 5-level page tables */ #define X86_FEATURE_RDPID (16*32+22) /* RDPID instruction */ #define X86_FEATURE_CLDEMOTE (16*32+25) /* CLDEMOTE instruction */ +#define X86_FEATURE_MOVDIRI (16*32+27) /* MOVDIRI instruction */
/* AMD-defined CPU features, CPUID level 0x80000007 (EBX), word 17 */ #define X86_FEATURE_OVERFLOW_RECOV (17*32+ 0) /* MCA overflow recovery support */