hypersparc dvma aliasing

hypersparc dvma aliasing

[Bob Breuer]

After further testing, it certainly seems that hypersparcs
have aliasing issues between dvma and physical addresses.

Here are some results that I get using a minimum of cache
flushing with 512K of cache, and all dvma areas are cacheable:

iommu_get_one -- cache(va) = cache(pa):
va 0xf0777000, pa 0x00777000, dvma 0xf0010000 -- fails
va 0xf0777000, pa 0x00777000, dvma 0xf0777000 -- works

iommu_map_dma_area -- cache(va) != cache(addr):
va 0xfbd66000, addr 0xfff0e000, pba 0xf0066000 -- fails
va 0xfbd80000, addr 0xfff00000, pba 0xf0000000 -- works
va 0xfbd66000, addr 0xfff0e000, pba 0xf010e000 -- works


I've got some additional changes that allocate dvma addresses
with the right cache color and allow for less cache flushing.
I will post a patch shortly.

Bob

Re: hypersparc dvma aliasing

[Bob Breuer]

Here's the preliminary patch.  This time around, both the hme
and esp drivers are working for me.  This replaces my previous
patch and is against the vanilla 2.6.9 kernel.  I've tried to
reduce the amount of unnecessary cache flushing, therefore this
will need some testing on non-hypersparc cpus also.  It needs
some cleanup yet, and will be rediffed against a later kernel.
I'm looking for comments and feedback.

Bob

--- linux-2.6.9/include/asm-sparc/bitext.h.orig	2004-10-18 16:54:40.000000000 -0500
+++ linux-2.6.9/include/asm-sparc/bitext.h	2004-11-15 23:41:03.000000000 -0600
@@ -17,6 +17,7 @@ struct bit_map {
  	int last_off;
  	int last_size;
  	int first_free;
+	int num_colors;
  };

  extern int bit_map_string_get(struct bit_map *t, int len, int align);
--- linux-2.6.9/arch/sparc/mm/iommu.c.orig	2004-10-18 16:55:29.000000000 -0500
+++ linux-2.6.9/arch/sparc/mm/iommu.c	2004-11-16 20:30:35.563411000 -0600
@@ -119,6 +119,11 @@ iommu_init(int iommund, struct sbus_bus
  		prom_halt();
  	}
  	bit_map_init(&iommu->usemap, bitmap, IOMMU_NPTES);
+	if (srmmu_modtype = HyperSparc)
+		/* fixme: use real cache size */
+		iommu->usemap.num_colors = (1<<20) >> PAGE_SHIFT;
+	else
+		iommu->usemap.num_colors = 1;

  	printk("IOMMU: impl %d vers %d table 0x%p[%d B] map [%d b]\n",
  	    impl, vers, iommu->page_table,
@@ -128,7 +133,9 @@ iommu_init(int iommund, struct sbus_bus
  }

  /* This begs to be btfixup-ed by srmmu. */
-static void iommu_viking_flush_iotlb(iopte_t *iopte, unsigned int niopte)
+/* Flush the iotlb entries to ram. */
+/* This could be better if we didn't have to flush whole pages. */
+static void iommu_flush_iotlb(iopte_t *iopte, unsigned int niopte)
  {
  	unsigned long start;
  	unsigned long end;
@@ -145,9 +152,16 @@ static void iommu_viking_flush_iotlb(iop
  			viking_flush_page(start);
  			start += PAGE_SIZE;
  		}
+	} else {
+		while(start < end) {
+			__flush_page_to_ram(start);
+			start += PAGE_SIZE;
+		}
  	}
  }

+//#define IOMMU_MAP_1TO1
+
  static u32 iommu_get_one(struct page *page, int npages, struct sbus_bus *sbus)
  {
  	struct iommu_struct *iommu = sbus->iommu;
@@ -156,7 +170,12 @@ static u32 iommu_get_one(struct page *pa
  	unsigned int busa, busa0;
  	int i;

-	ioptex = bit_map_string_get(&iommu->usemap, npages, 1);
+#ifdef IOMMU_MAP_1TO1
+	ioptex = page_to_pfn(page); /* physical address index */
+#else
+	/* page color = physical address */
+	ioptex = bit_map_string_get(&iommu->usemap, npages, page_to_pfn(page));
+#endif
  	if (ioptex < 0)
  		panic("iommu out");
  	busa0 = iommu->start + (ioptex << PAGE_SHIFT);
@@ -172,7 +191,7 @@ static u32 iommu_get_one(struct page *pa
  		page++;
  	}

-	iommu_viking_flush_iotlb(iopte0, npages);
+	iommu_flush_iotlb(iopte0, npages);

  	return busa0;
  }
@@ -286,7 +305,9 @@ static void iommu_release_one(u32 busa,
  		iommu_invalidate_page(iommu->regs, busa);
  		busa += PAGE_SIZE;
  	}
+#ifndef IOMMU_MAP_1TO1
  	bit_map_clear(&iommu->usemap, ioptex, npages);
+#endif
  }

  static void iommu_release_scsi_one(__u32 vaddr, unsigned long len, struct sbus_bus *sbus)
@@ -327,7 +348,13 @@ static int iommu_map_dma_area(dma_addr_t
  	if ((addr & ~PAGE_MASK) != 0) BUG();
  	if ((len & ~PAGE_MASK) != 0) BUG();

-	ioptex = bit_map_string_get(&iommu->usemap, len >> PAGE_SHIFT, 1);
+#ifdef IOMMU_MAP_1TO1
+	ioptex = (addr - iommu->start) >> PAGE_SHIFT;
+#else
+	/* page color = physical address */
+	ioptex = bit_map_string_get(&iommu->usemap, len >> PAGE_SHIFT,
+		addr >> PAGE_SHIFT);
+#endif
  	if (ioptex < 0)
  		panic("iommu out");

@@ -335,25 +362,28 @@ static int iommu_map_dma_area(dma_addr_t
  	first = iopte;
  	end = addr + len;
  	while(addr < end) {
+		pgd_t *pgdp;
+		pmd_t *pmdp;
+		pte_t *ptep;
+
  		page = va;
+
+		/* if we change to uncached, flush the cache first */
+		if (!(ioperm_noc & IOPTE_CACHE))
  		{
-			pgd_t *pgdp;
-			pmd_t *pmdp;
-			pte_t *ptep;
-
-			if (viking_mxcc_present)
-				viking_mxcc_flush_page(page);
-			else if (viking_flush)
+			if (viking_flush)
  				viking_flush_page(page);
  			else
+				/* Is everything else covered here? */
  				__flush_page_to_ram(page);
+		}

-			pgdp = pgd_offset(&init_mm, addr);
-			pmdp = pmd_offset(pgdp, addr);
-			ptep = pte_offset_map(pmdp, addr);
+		pgdp = pgd_offset(&init_mm, addr);
+		pmdp = pmd_offset(pgdp, addr);
+		ptep = pte_offset_map(pmdp, addr);
+
+		set_pte(ptep, mk_pte(virt_to_page(page), dvma_prot));

-			set_pte(ptep, mk_pte(virt_to_page(page), dvma_prot));
-		}
  		iopte_val(*iopte++)   		    MKIOPTE(page_to_pfn(virt_to_page(page)), ioperm_noc);
  		addr += PAGE_SIZE;
@@ -370,8 +400,16 @@ static int iommu_map_dma_area(dma_addr_t
  	 *        cpu mappings of pages potentially in the cpu caches, we have
  	 *        to handle the latter case as well.
  	 */
-	flush_cache_all();
-	iommu_viking_flush_iotlb(first, len >> PAGE_SHIFT);
+	/* With regards to cache flushing, there are 3 things to worry about:
+	 *
+	 * 1. the data in the region we are messing with
+	 *   - handled in the loop only if we are not I/O coherent
+	 * 2. the modified pte values
+	 *   - currently uncached
+	 * 3. the modifed iopte values
+	 *   - anything with a cache that is not write-through needs flushing
+	 */
+	iommu_flush_iotlb(first, len >> PAGE_SHIFT);
  	flush_tlb_all();
  	iommu_invalidate(iommu->regs);

@@ -392,12 +430,15 @@ static void iommu_unmap_dma_area(unsigne
  	iopte += ioptex;
  	end = busa + len;
  	while (busa < end) {
+		/* todo: restore pte changes done in iommu_map_dma_area */
  		iopte_val(*iopte++) = 0;
  		busa += PAGE_SIZE;
  	}
  	flush_tlb_all();
  	iommu_invalidate(iommu->regs);
+#ifndef IOMMU_MAP_1TO1
  	bit_map_clear(&iommu->usemap, ioptex, len >> PAGE_SHIFT);
+#endif
  }

  static struct page *iommu_translate_dvma(unsigned long busa)
--- linux-2.6.9/arch/sparc/mm/srmmu.c.orig	2004-10-18 16:54:32.000000000 -0500
+++ linux-2.6.9/arch/sparc/mm/srmmu.c	2004-11-16 20:33:36.923411000 -0600
@@ -90,8 +90,6 @@ ctxd_t *srmmu_context_table;
  int viking_mxcc_present;
  static spinlock_t srmmu_context_spinlock = SPIN_LOCK_UNLOCKED;

-int is_hypersparc;
-
  /*
   * In general all page table modifications should use the V8 atomic
   * swap instruction.  This insures the mmu and the cpu are in sync
@@ -565,7 +563,7 @@ static void srmmu_switch_mm(struct mm_st
  		srmmu_ctxd_set(&srmmu_context_table[mm->context], mm->pgd);
  	}

-	if (is_hypersparc)
+	if (srmmu_modtype = HyperSparc)
  		hyper_flush_whole_icache();

  	srmmu_set_context(mm->context);
@@ -1463,11 +1461,10 @@ static void __init poke_hypersparc(void)
  static void __init init_hypersparc(void)
  {
  	srmmu_name = "ROSS HyperSparc";
+	srmmu_modtype = HyperSparc;

  	init_vac_layout();

-	is_hypersparc = 1;
-
  	BTFIXUPSET_CALL(pte_clear, srmmu_pte_clear, BTFIXUPCALL_NORM);
  	BTFIXUPSET_CALL(pmd_clear, srmmu_pmd_clear, BTFIXUPCALL_NORM);
  	BTFIXUPSET_CALL(pgd_clear, srmmu_pgd_clear, BTFIXUPCALL_NORM);
--- linux-2.6.9/arch/sparc/lib/bitext.c.orig	2004-10-18 16:54:08.000000000 -0500
+++ linux-2.6.9/arch/sparc/lib/bitext.c	2004-11-15 23:54:04.000000000 -0600
@@ -29,10 +29,17 @@ int bit_map_string_get(struct bit_map *t
  	int offset, count;	/* siamese twins */
  	int off_new;
  	int align1;
-	int i;
+	int i, color;

-	if (align = 0)
-		align = 1;
+	if (t->num_colors) {
+		/* align is overloaded to be the page color */
+		color = align;
+		align = t->num_colors;
+	} else {
+		color = 0;
+		if (align = 0)
+			align = 1;
+	}
  	align1 = align - 1;
  	if ((align & align1) != 0)
  		BUG();
@@ -40,6 +47,7 @@ int bit_map_string_get(struct bit_map *t
  		BUG();
  	if (len <= 0 || len > t->size)
  		BUG();
+	color &= align1;

  	spin_lock(&t->lock);
  	if (len < t->last_size)
@@ -49,7 +57,7 @@ int bit_map_string_get(struct bit_map *t
  	count = 0;
  	for (;;) {
  		off_new = find_next_zero_bit(t->map, t->size, offset);
-		off_new = (off_new + align1) & ~align1;
+		off_new = ((off_new + align1) & ~align1) + color;
  		count += off_new - offset;
  		offset = off_new;
  		if (offset >= t->size)
@@ -69,6 +77,7 @@ int bit_map_string_get(struct bit_map *t
  		}

  		i = 0;
+		/* try using find_next_bit(t->map, len+1, offset) */
  		while (test_bit(offset + i, t->map) = 0) {
  			i++;
  			if (i = len) {
@@ -121,6 +130,8 @@ void bit_map_init(struct bit_map *t, uns
  	spin_lock_init(&t->lock);
  	t->map = map;
  	t->size = size;
-	t->last_size = 0;
-	t->first_free = 0;
+
+	// redundent, zeroed above
+	//t->last_size = 0;
+	//t->first_free = 0;
  }

Re: hypersparc dvma aliasing

[William Lee Irwin III]

On Tue, Nov 16, 2004 at 09:35:03PM -0600, Bob Breuer wrote:
> Here's the preliminary patch.  This time around, both the hme
> and esp drivers are working for me.  This replaces my previous
> patch and is against the vanilla 2.6.9 kernel.  I've tried to
> reduce the amount of unnecessary cache flushing, therefore this
> will need some testing on non-hypersparc cpus also.  It needs
> some cleanup yet, and will be rediffed against a later kernel.
> I'm looking for comments and feedback.

I'll spin this up on some sparc32 boxen.


-- wli

Re: hypersparc dvma aliasing

[David S. Miller]

On Tue, 16 Nov 2004 20:28:18 -0600
Bob Breuer <breuerr@mc.net> wrote:

> After further testing, it certainly seems that hypersparcs
> have aliasing issues between dvma and physical addresses.
> 
> Here are some results that I get using a minimum of cache
> flushing with 512K of cache, and all dvma areas are cacheable:
> 
> iommu_get_one -- cache(va) = cache(pa):
> va 0xf0777000, pa 0x00777000, dvma 0xf0010000 -- fails
> va 0xf0777000, pa 0x00777000, dvma 0xf0777000 -- works
> 
> iommu_map_dma_area -- cache(va) != cache(addr):
> va 0xfbd66000, addr 0xfff0e000, pba 0xf0066000 -- fails
> va 0xfbd80000, addr 0xfff00000, pba 0xf0000000 -- works
> va 0xfbd66000, addr 0xfff0e000, pba 0xf010e000 -- works

You've certainly disproven all the theories in my previous
email on this topic :-)  Good work Bob!

Re: hypersparc dvma aliasing

[Bob Breuer]

Hmmm, no reports on whether the previous patch works or not for anyone.
Well, I'll report my status.  Using Aurora 1.92, runlevel 2 works without
any major problems, but with runlevel 3 it looks like nfs is causing
problems, but I'm not certain.  I would like to know if it's just me,
or if it happens only with hypersparcs or any sparc32 machine.

In the meantime, I've revised the last patch.  This is against 2.6.10-rc2
and is just enough to fix the hypersparc dvma problems.  The other changes
can be looked at later.

If anyone has a more elegant solution than my overloading of the align
argument to bit_map_string_get(), let me know.  The alignment for page
coloring is known ahead of time, so we only need to pass either the
alignment or the page color hint.

Then when setting up the number of colors, where can I get the proper
cache size from?  I've only enabled the page coloring for hypersparcs,
should we do the coloring for the rest as well?

Bob


diff -X dontdiff -urp linux-2.6.10-rc2-clean/include/asm-sparc/bitext.h linux-2.6.10-rc2/include/asm-sparc/bitext.h
--- linux-2.6.10-rc2-clean/include/asm-sparc/bitext.h	2004-10-18 16:54:40.000000000 -0500
+++ linux-2.6.10-rc2/include/asm-sparc/bitext.h	2004-11-19 23:08:08.000000000 -0600
@@ -17,6 +17,7 @@ struct bit_map {
  	int last_off;
  	int last_size;
  	int first_free;
+	int num_colors;
  };

  extern int bit_map_string_get(struct bit_map *t, int len, int align);
diff -X dontdiff -urp linux-2.6.10-rc2-clean/arch/sparc/lib/bitext.c linux-2.6.10-rc2/arch/sparc/lib/bitext.c
--- linux-2.6.10-rc2-clean/arch/sparc/lib/bitext.c	2004-11-21 14:58:21.000000000 -0600
+++ linux-2.6.10-rc2/arch/sparc/lib/bitext.c	2004-11-21 17:59:45.000000000 -0600
@@ -29,10 +29,17 @@ int bit_map_string_get(struct bit_map *t
  	int offset, count;	/* siamese twins */
  	int off_new;
  	int align1;
-	int i;
+	int i, color;

-	if (align = 0)
-		align = 1;
+	if (t->num_colors) {
+		/* align is overloaded to be the page color */
+		color = align;
+		align = t->num_colors;
+	} else {
+		color = 0;
+		if (align = 0)
+			align = 1;
+	}
  	align1 = align - 1;
  	if ((align & align1) != 0)
  		BUG();
@@ -40,6 +47,7 @@ int bit_map_string_get(struct bit_map *t
  		BUG();
  	if (len <= 0 || len > t->size)
  		BUG();
+	color &= align1;

  	spin_lock(&t->lock);
  	if (len < t->last_size)
@@ -49,7 +57,7 @@ int bit_map_string_get(struct bit_map *t
  	count = 0;
  	for (;;) {
  		off_new = find_next_zero_bit(t->map, t->size, offset);
-		off_new = (off_new + align1) & ~align1;
+		off_new = ((off_new + align1) & ~align1) + color;
  		count += off_new - offset;
  		offset = off_new;
  		if (offset >= t->size)
@@ -121,6 +129,4 @@ void bit_map_init(struct bit_map *t, uns
  	spin_lock_init(&t->lock);
  	t->map = map;
  	t->size = size;
-	t->last_size = 0;
-	t->first_free = 0;
  }
diff -X dontdiff -urp linux-2.6.10-rc2-clean/arch/sparc/mm/iommu.c linux-2.6.10-rc2/arch/sparc/mm/iommu.c
--- linux-2.6.10-rc2-clean/arch/sparc/mm/iommu.c	2004-11-21 14:58:22.000000000 -0600
+++ linux-2.6.10-rc2/arch/sparc/mm/iommu.c	2004-11-21 18:09:28.000000000 -0600
@@ -119,6 +119,14 @@ iommu_init(int iommund, struct sbus_bus
  		prom_halt();
  	}
  	bit_map_init(&iommu->usemap, bitmap, IOMMU_NPTES);
+	/* To be coherent on HyperSparc, the page color of DVMA
+	 * and physical addresses must match.
+	 */
+	if (srmmu_modtype = HyperSparc)
+		/* XXX Use real cache size */
+		iommu->usemap.num_colors = (1<<20) >> PAGE_SHIFT;
+	else
+		iommu->usemap.num_colors = 1;

  	printk("IOMMU: impl %d vers %d table 0x%p[%d B] map [%d b]\n",
  	    impl, vers, iommu->page_table,
@@ -128,7 +136,9 @@ iommu_init(int iommund, struct sbus_bus
  }

  /* This begs to be btfixup-ed by srmmu. */
-static void iommu_viking_flush_iotlb(iopte_t *iopte, unsigned int niopte)
+/* Flush the iotlb entries to ram. */
+/* This could be better if we didn't have to flush whole pages. */
+static void iommu_flush_iotlb(iopte_t *iopte, unsigned int niopte)
  {
  	unsigned long start;
  	unsigned long end;
@@ -145,6 +155,11 @@ static void iommu_viking_flush_iotlb(iop
  			viking_flush_page(start);
  			start += PAGE_SIZE;
  		}
+	} else {
+		while(start < end) {
+			__flush_page_to_ram(start);
+			start += PAGE_SIZE;
+		}
  	}
  }

@@ -156,7 +171,8 @@ static u32 iommu_get_one(struct page *pa
  	unsigned int busa, busa0;
  	int i;

-	ioptex = bit_map_string_get(&iommu->usemap, npages, 1);
+	/* page color = pfn of page */
+	ioptex = bit_map_string_get(&iommu->usemap, npages, page_to_pfn(page));
  	if (ioptex < 0)
  		panic("iommu out");
  	busa0 = iommu->start + (ioptex << PAGE_SHIFT);
@@ -172,8 +188,7 @@ static u32 iommu_get_one(struct page *pa
  		page++;
  	}

-	iommu_viking_flush_iotlb(iopte0, npages);
-	flush_cache_all(); // hack to fix dma errors with hypersparc
+	iommu_flush_iotlb(iopte0, npages);

  	return busa0;
  }
@@ -328,7 +343,9 @@ static int iommu_map_dma_area(dma_addr_t
  	if ((addr & ~PAGE_MASK) != 0) BUG();
  	if ((len & ~PAGE_MASK) != 0) BUG();

-	ioptex = bit_map_string_get(&iommu->usemap, len >> PAGE_SHIFT, 1);
+	/* page color = physical address */
+	ioptex = bit_map_string_get(&iommu->usemap, len >> PAGE_SHIFT,
+		addr >> PAGE_SHIFT);
  	if (ioptex < 0)
  		panic("iommu out");

@@ -372,7 +389,7 @@ static int iommu_map_dma_area(dma_addr_t
  	 *        to handle the latter case as well.
  	 */
  	flush_cache_all();
-	iommu_viking_flush_iotlb(first, len >> PAGE_SHIFT);
+	iommu_flush_iotlb(first, len >> PAGE_SHIFT);
  	flush_tlb_all();
  	iommu_invalidate(iommu->regs);

Re: hypersparc dvma aliasing

[David S. Miller]

On Tue, 23 Nov 2004 00:18:48 -0600
Bob Breuer <breuerr@mc.net> wrote:

> Then when setting up the number of colors, where can I get the proper
> cache size from?  I've only enabled the page coloring for hypersparcs,
> should we do the coloring for the rest as well?

Use vac_cache_size on srmmu.

Re: hypersparc dvma aliasing

[Stan Benoit]

On Tue, Nov 23, 2004 at 12:18:48AM -0600, Bob Breuer wrote:
> Hmmm, no reports on whether the previous patch works or 
not for anyone.
> diff -X dontdiff -urp linux-2.6.10-rc2-clean

Bob are you using 2.6.10-rc2 from  
ftp://ftp.kernel.org/pub/linux/kernel/v2.6/testing/ 
or linux-2.6.9 patched with your fixes? 
Need a good start point. Both my Ross hypersparc 150 smp ss20 and 
supersparc 75 smp ss20 have Aurora build 1.0 installed. 
They are ready to go. 

--
Stan Benoit<sbenoit@verizon.net>

Re: hypersparc dvma aliasing

[Bob Breuer]

Stan Benoit wrote:
> On Tue, Nov 23, 2004 at 12:18:48AM -0600, Bob Breuer wrote:
> 
>>Hmmm, no reports on whether the previous patch works or 
>> not for anyone.
> 
>>diff -X dontdiff -urp linux-2.6.10-rc2-clean
> 
> 
> Bob are you using 2.6.10-rc2 from  
> ftp://ftp.kernel.org/pub/linux/kernel/v2.6/testing/ 
> or linux-2.6.9 patched with your fixes? 
> Need a good start point. Both my Ross hypersparc 150 smp ss20 and 
> supersparc 75 smp ss20 have Aurora build 1.0 installed. 
> They are ready to go. 
> 

I've tried both kernels.  The previous 2 line fix made it into
2.6.10-rc2, so that is what I'm basing any future diffs off of.

I'd recommend upgrading Aurora to 1.92 because 1.0 may not support
a 2.6 kernel (see the aurora-sparc-user list archives for help).
Be sure to keep a 2.4 kernel around to fall back to.

If it will help anyone with testing, I may be able to provide an
already compiled kernel and modules.

Bob

Re: hypersparc dvma aliasing

[Stan Benoit]

On Tue, Nov 23, 2004 at 09:35:47AM -0600, Bob Breuer wrote:
> If it will help anyone with testing, I may be able to provide an
> already compiled kernel and modules.
> 
> Bob
That looks like a good idea, that should sync everything up real nice.

-- 
Stan Benoit<sbenoit@verizon.net>
Mondo Testing	http://troff.nakedsoul.org

Re: hypersparc dvma aliasing

[William Lee Irwin III]

Stan Benoit wrote:
>> Bob are you using 2.6.10-rc2 from  
>> ftp://ftp.kernel.org/pub/linux/kernel/v2.6/testing/ 
>> or linux-2.6.9 patched with your fixes? 
>> Need a good start point. Both my Ross hypersparc 150 smp ss20 and 
>> supersparc 75 smp ss20 have Aurora build 1.0 installed. 
>> They are ready to go. 

On Tue, Nov 23, 2004 at 09:35:47AM -0600, Bob Breuer wrote:
> I've tried both kernels.  The previous 2 line fix made it into
> 2.6.10-rc2, so that is what I'm basing any future diffs off of.
> I'd recommend upgrading Aurora to 1.92 because 1.0 may not support
> a 2.6 kernel (see the aurora-sparc-user list archives for help).
> Be sure to keep a 2.4 kernel around to fall back to.
> If it will help anyone with testing, I may be able to provide an
> already compiled kernel and modules.

I didn't forget about this. The results on 2.6.10-rc2-mm3 were so
catastrophic I'm still trying to debug them.


-- wli