Re: [PATCH -v2 1/2] x86: Reserve [0xa0000, 0x100000] in e820 map

[Yinghai <yinghai.lu@oracle.com>]

On 04/13/2010 02:58 PM, H. Peter Anvin wrote:
> On 04/13/2010 02:42 PM, Yinghai wrote:
>> On 04/13/2010 02:18 PM, H. Peter Anvin wrote:
>>> On 04/13/2010 02:11 PM, Yinghai wrote:
>>>>>
>>>>> I guess the real question (which I haven't looked at myself) is if the
>>>>> E820_RESERVED -> BUSY will cause an explicitly assigned BAR from being
>>>>> moved.  That's bad, not so much for this particular range, but from BARs
>>>>> which may be assigned by SMM.  Hacking that up in a simulator
>>>>> (Qemu/Bochs) and testing it is probably on the to do list...
>>>>
>>>> no, if some device BAR fall in that range, it should still use that range, and will not be relocated.
>>>>
>>>> will update the change log.
>>>>
>>>
>>> Good, that's what we want.
>>
>> the driver for that device later can not use pci_request_region(). because that region is BUSY already.
>>
> 
> That's not good (in general - for devices in this particular range it's
> not such a big deal, but it is potentially really bad for devices marked
> reserved for them not to be moved.)
> 
> We have talked about a need to resolve this before.

this one should make both cases work.

Andy, can you check this one together with
v3: x86: Reserve [0xa0000, 0x100000] in e820 map

Guenter, can you try the two patches on the system with special device?

Thanks

Yinghai

--------

Subject: [PATCH] x86, resource: Add reserve_region_with_split_check_child()

It will cover the whole region to BUSY, except that some regions that have
children under them.

those children normally is PCI bar but it is falling into E820_RESERVED.
We can not put BUSY on them, otherwise driver can not use pci_request_region()
later

/proc/iomem will have
00010000-00094fff : System RAM
00095000-0009ffff : reserved
000a0000-000bffff : PCI Bus 0000:00
  000a0000-000bffff : reserved
000c0000-000cffff : reserved
000d0000-000dffff : PCI Bus 0000:00
  000d0000-000dffff : reserved
000e0000-000fffff : reserved

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/kernel/e820.c |   10 +++++++---
 include/linux/ioport.h |    3 +++
 kernel/resource.c      |   24 +++++++++++++++++++-----
 3 files changed, 29 insertions(+), 8 deletions(-)

Index: linux-2.6/arch/x86/kernel/e820.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820.c
+++ linux-2.6/arch/x86/kernel/e820.c
@@ -1094,7 +1094,7 @@ void __init e820_reserve_resources(void)
 		 * pci device BAR resource and insert them later in
 		 * pcibios_resource_survey()
 		 */
-		if (e820.map[i].type != E820_RESERVED || res->start < (1ULL<<20)) {
+		if (e820.map[i].type != E820_RESERVED) {
 			res->flags |= IORESOURCE_BUSY;
 			insert_resource(&iomem_resource, res);
 		}
@@ -1135,8 +1135,12 @@ void __init e820_reserve_resources_late(
 
 	res = e820_res;
 	for (i = 0; i < e820.nr_map; i++) {
-		if (!res->parent && res->end)
-			insert_resource_expand_to_fit(&iomem_resource, res);
+		if (!res->parent && res->end) {
+			if (res->start < (1ULL<<20)) {
+				reserve_region_with_split_check_child(&iomem_resource, res->start, res->end, res->name);
+			} else
+				insert_resource_expand_to_fit(&iomem_resource, res);
+		}
 		res++;
 	}
 
Index: linux-2.6/include/linux/ioport.h
===================================================================
--- linux-2.6.orig/include/linux/ioport.h
+++ linux-2.6/include/linux/ioport.h
@@ -120,6 +120,9 @@ void release_child_resources(struct reso
 extern void reserve_region_with_split(struct resource *root,
 			     resource_size_t start, resource_size_t end,
 			     const char *name);
+void reserve_region_with_split_check_child(struct resource *root,
+			     resource_size_t start, resource_size_t end,
+			     const char *name);
 extern struct resource *insert_resource_conflict(struct resource *parent, struct resource *new);
 extern int insert_resource(struct resource *parent, struct resource *new);
 extern void insert_resource_expand_to_fit(struct resource *root, struct resource *new);
Index: linux-2.6/kernel/resource.c
===================================================================
--- linux-2.6.orig/kernel/resource.c
+++ linux-2.6/kernel/resource.c
@@ -609,7 +609,7 @@ int adjust_resource(struct resource *res
 
 static void __init __reserve_region_with_split(struct resource *root,
 		resource_size_t start, resource_size_t end,
-		const char *name)
+		const char *name, bool check_child)
 {
 	struct resource *parent = root;
 	struct resource *conflict;
@@ -631,13 +631,18 @@ static void __init __reserve_region_with
 	kfree(res);
 
 	/* conflict covered whole area */
-	if (conflict->start <= start && conflict->end >= end)
+	if (conflict->start <= start && conflict->end >= end) {
+		if (check_child && !conflict->child && strstr(conflict->name, "PCI Bus"))
+			__reserve_region_with_split(conflict, start, end, name, false);
 		return;
+	}
 
 	if (conflict->start > start)
-		__reserve_region_with_split(root, start, conflict->start-1, name);
+		__reserve_region_with_split(root, start, conflict->start-1, name, check_child);
 	if (conflict->end < end)
-		__reserve_region_with_split(root, conflict->end+1, end, name);
+		__reserve_region_with_split(root, conflict->end+1, end, name, check_child);
+	if (check_child && !conflict->child && strstr(conflict->name, "PCI Bus"))
+		__reserve_region_with_split(conflict, conflict->start, conflict->end, name, false);
 }
 
 void __init reserve_region_with_split(struct resource *root,
@@ -645,7 +650,16 @@ void __init reserve_region_with_split(st
 		const char *name)
 {
 	write_lock(&resource_lock);
-	__reserve_region_with_split(root, start, end, name);
+	__reserve_region_with_split(root, start, end, name, false);
+	write_unlock(&resource_lock);
+}
+
+void __init reserve_region_with_split_check_child(struct resource *root,
+		resource_size_t start, resource_size_t end,
+		const char *name)
+{
+	write_lock(&resource_lock);
+	__reserve_region_with_split(root, start, end, name, true);
 	write_unlock(&resource_lock);
 }