From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zachary Amsden Subject: RFC: const_udelay in 018-delay functions patch Date: Tue, 24 Oct 2006 22:11:10 -0700 Message-ID: <453EF1EE.2000503@vmware.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------060103000703060302020304" Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.osdl.org Errors-To: virtualization-bounces@lists.osdl.org To: Chris Wright , Rusty Russell , Virtualization Mailing List , Jeremy Fitzhardinge List-Id: virtualization@lists.linuxfoundation.org This is a multi-part message in MIME format. --------------060103000703060302020304 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit So I implemented udelay and ndelay through a single paravirt_op, const_udelay, instead of having either two separate paravirt-ops for udelay or ndelay, or a redundant const_udelay paravirt_op. Anybody have any objection to reworking the patch this way? --------------060103000703060302020304 Content-Type: text/plain; name="018-delay-functions.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="018-delay-functions.patch" Add paravirtualized delay mechanisms to paravirt-ops. There are two delays used by native hardware that are unnecessary inside a virtual machine. The first of these is the hardware I/O delay used by io.h. The second is udelay, which is used in many places. The only code that actually depends on a real time delay in a virtual machine is SMP bootstrapping, which must wait for the APs to come online. For this purpose, I have introduced a way to override the paravirt-ops implementation, by defining USE_REAL_TIME_DELAY before the header files are included. Similarly, the boot decompressor uses I/O instructions, and it cannot yet use the paravirt-ops versions. So it must undefine CONFIG_PARAVIRT to prevent io_delay from being redefined. Signed-off-by: Zachary Amsden =================================================================== --- a/arch/i386/boot/compressed/misc.c +++ b/arch/i386/boot/compressed/misc.c @@ -9,6 +9,7 @@ * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996 */ +#undef CONFIG_PARAVIRT #include #include #include =================================================================== --- a/arch/i386/kernel/paravirt.c +++ b/arch/i386/kernel/paravirt.c @@ -21,6 +21,7 @@ #include #include #include +#include static fastcall void native_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx, unsigned int *edx) @@ -328,6 +329,11 @@ static fastcall void native_set_iopl_mas "popfl" : "=&r" (reg) : "i" (~X86_EFLAGS_IOPL), "r" (mask)); +} + +static fastcall void native_io_delay(void) +{ + asm volatile("outb %al,$0x80"); } /* These are in entry.S */ @@ -445,6 +451,9 @@ struct paravirt_ops paravirt_ops = { .write_idt_entry = native_write_idt_entry, .set_iopl_mask = native_set_iopl_mask, + .io_delay = native_io_delay, + .const_udelay = __const_udelay, + .irq_enable_sysexit = native_irq_enable_sysexit, .iret = native_iret, }; =================================================================== --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -33,6 +33,11 @@ * Dave Jones : Report invalid combinations of Athlon CPUs. * Rusty Russell : Hacked into shape for new "hotplug" boot process. */ + +/* SMP boot always wants to use real time delay to allow sufficient time for + * the APs to come online */ +#define USE_REAL_TIME_DELAY + #include #include #include =================================================================== --- a/drivers/net/de600.c +++ b/drivers/net/de600.c @@ -43,7 +43,6 @@ static const char version[] = "de600.c: * modify the following "#define": (see for more info) #define REALLY_SLOW_IO */ -#define SLOW_IO_BY_JUMPING /* Looks "better" than dummy write to port 0x80 :-) */ /* use 0 for production, 1 for verification, >2 for debug */ #ifdef DE600_DEBUG =================================================================== --- a/include/asm-i386/delay.h +++ b/include/asm-i386/delay.h @@ -15,6 +15,13 @@ extern void __const_udelay(unsigned long extern void __const_udelay(unsigned long usecs); extern void __delay(unsigned long loops); +#if defined(CONFIG_PARAVIRT) && !defined(USE_REAL_TIME_DELAY) +#define udelay(n) paravirt_ops.const_udelay((n) * 0x10c7ul) + +#define ndelay(n) paravirt_ops.const_udelay((n) * 5ul) + +#else /* !PARAVIRT || USE_REAL_TIME_DELAY */ + #define udelay(n) (__builtin_constant_p(n) ? \ ((n) > 20000 ? __bad_udelay() : __const_udelay((n) * 0x10c7ul)) : \ __udelay(n)) @@ -22,6 +29,7 @@ extern void __delay(unsigned long loops) #define ndelay(n) (__builtin_constant_p(n) ? \ ((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \ __ndelay(n)) +#endif void use_tsc_delay(void); =================================================================== --- a/include/asm-i386/io.h +++ b/include/asm-i386/io.h @@ -256,11 +256,11 @@ static inline void flush_write_buffers(v #endif /* __KERNEL__ */ -#ifdef SLOW_IO_BY_JUMPING -#define __SLOW_DOWN_IO "jmp 1f; 1: jmp 1f; 1:" -#else +#if defined(CONFIG_PARAVIRT) && !defined(USE_REAL_IO) +#include +#else + #define __SLOW_DOWN_IO "outb %%al,$0x80;" -#endif static inline void slow_down_io(void) { __asm__ __volatile__( @@ -270,6 +270,8 @@ static inline void slow_down_io(void) { #endif : : ); } + +#endif #ifdef CONFIG_X86_NUMAQ extern void *xquad_portio; /* Where the IO area was mapped */ =================================================================== --- a/include/asm-i386/paravirt.h +++ b/include/asm-i386/paravirt.h @@ -98,6 +98,11 @@ struct paravirt_ops void (fastcall *write_idt_entry)(void *dt, int entrynum, u64 entry); void (fastcall *set_iopl_mask)(unsigned mask); + void (fastcall *io_delay)(void); + + /* The native equivalents that are not fastcall, and presumably + * a nop in a VM, although driver domains may want real delay. */ + void (*const_udelay)(unsigned long loops); /* These two are jmp to, not actually called. */ void (fastcall *irq_enable_sysexit)(void); @@ -224,6 +229,16 @@ static inline char *memory_setup(void) return paravirt_ops.memory_setup(); } +/* The paravirtualized I/O functions */ +static inline void slow_down_io(void) { + paravirt_ops.io_delay(); +#ifdef REALLY_SLOW_IO + paravirt_ops.io_delay(); + paravirt_ops.io_delay(); + paravirt_ops.io_delay(); +#endif +} + /* These all sit in the .parainstructions section to tell us what to patch. */ struct paravirt_patch { u8 *instr; /* original instructions */ --------------060103000703060302020304 Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline _______________________________________________ Virtualization mailing list Virtualization@lists.osdl.org https://lists.osdl.org/mailman/listinfo/virtualization --------------060103000703060302020304--