As was done in r195820 for amd64, use clflush for flushing cache lines

when memory page caching attributes changed, and CPU does not support
self-snoop, but implemented clflush, for i386.

Take care of possible mappings of the page by sf buffer by utilizing
the mapping for clflush, otherwise map the page transiently. Amd64
used direct map.

Proposed and reviewed by:  alc
Approved by:   re (kensmith)

sys/i386/i386/initcpu.c

@@ -91,6 +91,7 @@ u_int	cpu_procinfo = 0;	/* HyperThreading Info / Brand Index / CLFUSH */
 u_int	cpu_procinfo2 = 0;	/* Multicore info */
 char	cpu_vendor[20] = "";	/* CPU Origin code */
 u_int	cpu_vendor_id = 0;	/* CPU vendor ID */
+u_int	cpu_clflush_line_size = 32;
 
 SYSCTL_UINT(_hw, OID_AUTO, via_feature_rng, CTLFLAG_RD,
 	&via_feature_rng, 0, "VIA C3/C7 RNG feature available in CPU");
@@ -709,6 +710,14 @@ initializecpu(void)
 	}
 	enable_sse();
 
+	/*
+	 * CPUID with %eax = 1, %ebx returns
+	 * Bits 15-8: CLFLUSH line size
+	 * 	(Value * 8 = cache line size in bytes)
+	 */
+	if ((cpu_feature & CPUID_CLFSH) != 0)
+		cpu_clflush_line_size = ((cpu_procinfo >> 8) & 0xff) * 8;
+
 #if defined(PC98) && !defined(CPU_UPGRADE_HW_CACHE)
 	/*
 	 * OS should flush L1 cache by itself because no PC-98 supports

sys/i386/i386/pmap.c

@@ -119,6 +119,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/msgbuf.h>
 #include <sys/mutex.h>
 #include <sys/proc.h>
+#include <sys/sf_buf.h>
 #include <sys/sx.h>
 #include <sys/vmmeter.h>
 #include <sys/sched.h>
@@ -732,7 +733,7 @@ SYSCTL_ULONG(_vm_pmap_pde, OID_AUTO, promotions, CTLFLAG_RD,
  * Determine the appropriate bits to set in a PTE or PDE for a specified
  * caching mode.
  */
-static int
+int
 pmap_cache_bits(int mode, boolean_t is_pde)
 {
 	int pat_flag, pat_index, cache_bits;
@@ -945,6 +946,40 @@ pmap_invalidate_cache(void)
 }
 #endif /* !SMP */
 
+void
+pmap_invalidate_cache_range(vm_offset_t sva, vm_offset_t eva)
+{
+
+	KASSERT((sva & PAGE_MASK) == 0,
+	    ("pmap_invalidate_cache_range: sva not page-aligned"));
+	KASSERT((eva & PAGE_MASK) == 0,
+	    ("pmap_invalidate_cache_range: eva not page-aligned"));
+
+	if (cpu_feature & CPUID_SS)
+		; /* If "Self Snoop" is supported, do nothing. */
+	else if (cpu_feature & CPUID_CLFSH) {
+
+		/*
+		 * Otherwise, do per-cache line flush.  Use the mfence
+		 * instruction to insure that previous stores are
+		 * included in the write-back.  The processor
+		 * propagates flush to other processors in the cache
+		 * coherence domain.
+		 */
+		mfence();
+		for (; eva < sva; eva += cpu_clflush_line_size)
+			clflush(eva);
+		mfence();
+	} else {
+
+		/*
+		 * No targeted cache flush methods are supported by CPU,
+		 * globally invalidate cache as a last resort.
+		 */
+		pmap_invalidate_cache();
+	}
+}
+
 /*
  * Are we current address space or kernel?  N.B. We return FALSE when
  * a pmap's page table is in use because a kernel thread is borrowing
@@ -4400,7 +4435,8 @@ pmap_clear_reference(vm_page_t m)
 void *
 pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
 {
-	vm_offset_t va, tmpva, offset;
+	vm_offset_t va, offset;
+	vm_size_t tmpsize;
 
 	offset = pa & PAGE_MASK;
 	size = roundup(offset + size, PAGE_SIZE);
@@ -4413,16 +4449,10 @@ pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
 	if (!va)
 		panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
 
-	for (tmpva = va; size > 0; ) {
-		pmap_kenter_attr(tmpva, pa, mode);
-		size -= PAGE_SIZE;
-		tmpva += PAGE_SIZE;
-		pa += PAGE_SIZE;
-	}
-	pmap_invalidate_range(kernel_pmap, va, tmpva);
-	/* If "Self Snoop" is supported, do nothing. */
-	if (!(cpu_feature & CPUID_SS))
-		pmap_invalidate_cache();
+	for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE)
+		pmap_kenter_attr(va + tmpsize, pa + tmpsize, mode);
+	pmap_invalidate_range(kernel_pmap, va, va + tmpsize);
+	pmap_invalidate_cache_range(va, va + size);
 	return ((void *)(va + offset));
 }
 
@@ -4462,16 +4492,48 @@ pmap_unmapdev(vm_offset_t va, vm_size_t size)
 void
 pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
 {
+	struct sysmaps *sysmaps;
+	vm_offset_t sva, eva;
 
 	m->md.pat_mode = ma;
+	if ((m->flags & PG_FICTITIOUS) != 0)
+		return;
 
 	/*
 	 * If "m" is a normal page, flush it from the cache.
+	 * See pmap_invalidate_cache_range().
+	 *
+	 * First, try to find an existing mapping of the page by sf
+	 * buffer. sf_buf_invalidate_cache() modifies mapping and
+	 * flushes the cache.
 	 */    
-	if ((m->flags & PG_FICTITIOUS) == 0) {
-		/* If "Self Snoop" is supported, do nothing. */
-		if (!(cpu_feature & CPUID_SS))
-			pmap_invalidate_cache();
+	if (sf_buf_invalidate_cache(m))
+		return;
+
+	/*
+	 * If page is not mapped by sf buffer, but CPU does not
+	 * support self snoop, map the page transient and do
+	 * invalidation. In the worst case, whole cache is flushed by
+	 * pmap_invalidate_cache_range().
+	 */
+	if ((cpu_feature & (CPUID_SS|CPUID_CLFSH)) == CPUID_CLFSH) {
+		sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)];
+		mtx_lock(&sysmaps->lock);
+		if (*sysmaps->CMAP2)
+			panic("pmap_page_set_memattr: CMAP2 busy");
+		sched_pin();
+		*sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(m) |
+		    PG_A | PG_M | pmap_cache_bits(m->md.pat_mode, 0);
+		invlcaddr(sysmaps->CADDR2);
+		sva = (vm_offset_t)sysmaps->CADDR2;
+		eva = sva + PAGE_SIZE;
+	} else
+		sva = eva = 0; /* gcc */
+	pmap_invalidate_cache_range(sva, eva);
+	if (sva != 0) {
+		*sysmaps->CMAP2 = 0;
+		sched_unpin();
+		mtx_unlock(&sysmaps->lock);
 	}
 }
 
@@ -4537,9 +4599,7 @@ pmap_change_attr(vm_offset_t va, vm_size_t size, int mode)
 	 */    
 	if (changed) {
 		pmap_invalidate_range(kernel_pmap, base, tmpva);
-		/* If "Self Snoop" is supported, do nothing. */
-		if (!(cpu_feature & CPUID_SS))
-			pmap_invalidate_cache();
+		pmap_invalidate_cache_range(base, tmpva);
 	}
 	return (0);
 }

sys/i386/i386/vm_machdep.c

@@ -719,6 +719,39 @@ sf_buf_init(void *arg)
 	mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
 }
 
+/*
+ * Invalidate the cache lines that may belong to the page, if
+ * (possibly old) mapping of the page by sf buffer exists.  Returns
+ * TRUE when mapping was found and cache invalidated.
+ */
+boolean_t
+sf_buf_invalidate_cache(vm_page_t m)
+{
+	struct sf_head *hash_list;
+	struct sf_buf *sf;
+	boolean_t ret;
+
+	hash_list = &sf_buf_active[SF_BUF_HASH(m)];
+	ret = FALSE;
+	mtx_lock(&sf_buf_lock);
+	LIST_FOREACH(sf, hash_list, list_entry) {
+		if (sf->m == m) {
+			/*
+			 * Use pmap_qenter to update the pte for
+			 * existing mapping, in particular, the PAT
+			 * settings are recalculated.
+			 */
+			pmap_qenter(sf->kva, &m, 1);
+			pmap_invalidate_cache_range(sf->kva, sf->kva +
+			    PAGE_SIZE);
+			ret = TRUE;
+			break;
+		}
+	}
+	mtx_unlock(&sf_buf_lock);
+	return (ret);
+}
+
 /*
  * Get an sf_buf from the freelist.  May block if none are available.
  */
@@ -787,9 +820,10 @@ sf_buf_alloc(struct vm_page *m, int flags)
 	opte = *ptep;
 #ifdef XEN
        PT_SET_MA(sf->kva, xpmap_ptom(VM_PAGE_TO_PHYS(m)) | pgeflag
-	   | PG_RW | PG_V);
+	   | PG_RW | PG_V | pmap_cache_bits(m->md.pat_mode, 0));
 #else
-	*ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V;
+	*ptep = VM_PAGE_TO_PHYS(m) | pgeflag | PG_RW | PG_V |
+	    pmap_cache_bits(m->md.pat_mode, 0);
 #endif
 
 	/*

sys/i386/include/cpufunc.h

@@ -89,6 +89,13 @@ bsrl(u_int mask)
 	return (result);
 }
 
+static __inline void
+clflush(u_long addr)
+{
+
+	__asm __volatile("clflush %0" : : "m" (*(char *)addr));
+}
+
 static __inline void
 disable_intr(void)
 {
@@ -138,6 +145,13 @@ cpu_mwait(int extensions, int hints)
 	__asm __volatile("mwait;" : :"a" (hints), "c" (extensions));
 }
 
+static __inline void
+mfence(void)
+{
+
+	__asm __volatile("mfence" : : : "memory");
+}
+
 #ifdef _KERNEL
 
 #define	HAVE_INLINE_FFS

sys/i386/include/md_var.h

@@ -52,6 +52,7 @@ extern	u_int	amd_feature2;
 extern	u_int	amd_pminfo;
 extern	u_int	via_feature_rng;
 extern	u_int	via_feature_xcrypt;
+extern	u_int	cpu_clflush_line_size;
 extern	u_int	cpu_fxsr;
 extern	u_int	cpu_high;
 extern	u_int	cpu_id;

sys/i386/include/pmap.h

@@ -463,6 +463,7 @@ extern vm_offset_t virtual_end;
 #define	pmap_unmapbios(va, sz)	pmap_unmapdev((va), (sz))
 
 void	pmap_bootstrap(vm_paddr_t);
+int	pmap_cache_bits(int mode, boolean_t is_pde);
 int	pmap_change_attr(vm_offset_t, vm_size_t, int);
 void	pmap_init_pat(void);
 void	pmap_kenter(vm_offset_t va, vm_paddr_t pa);
@@ -480,6 +481,7 @@ void	pmap_invalidate_page(pmap_t, vm_offset_t);
 void	pmap_invalidate_range(pmap_t, vm_offset_t, vm_offset_t);
 void	pmap_invalidate_all(pmap_t);
 void	pmap_invalidate_cache(void);
+void	pmap_invalidate_cache_range(vm_offset_t, vm_offset_t);
 
 #endif /* _KERNEL */
 

sys/i386/include/sf_buf.h

@@ -58,4 +58,6 @@ sf_buf_page(struct sf_buf *sf)
 	return (sf->m);
 }
 
+boolean_t sf_buf_invalidate_cache(vm_page_t m);
+
 #endif /* !_MACHINE_SF_BUF_H_ */