On Wed, 2016-05-25 at 01:33 +0200, Luis R. Rodriguez wrote:

On Wed, Apr 27, 2016 at 09:25:57AM -0600, Toshi Kani wrote:

quoted

On x86, ioremap() and remap_pfn_range() fail on conflicting cache
type of an alias mapping request only if the case is not allowed
by the rule set in is_new_memtype_allowed(). While this exemption
is necessary for remap_pfn_range() called for /dev/mem mappings,
it is not necessary for ioremap().

The wording here is a bit unclear. How about:

I will update the change log according to your suggestions.

quoted

Link: https://lkml.org/lkml/2016/4/16/54

lkml.org references should be avoided, we have no control over
that domain. Please instead use:

http://lkml.kernel.org/r/20160416092018.GA8453@gmail.com

Will do.

quoted

Signed-off-by: Toshi Kani <redacted>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <redacted>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <redacted>
Cc: Luis R. Rodriguez <redacted>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dan Williams <redacted>
---
 arch/x86/mm/ioremap.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 0d8d53d..16c5887 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c

@@ -138,14 +138,16 @@ static void __iomem

*__ioremap_caller(resource_size_t phys_addr,
 	}
 
 	if (pcm != new_pcm) {
-		if (!is_new_memtype_allowed(phys_addr, size, pcm,
new_pcm)) {
-			printk(KERN_ERR
-		"ioremap error for 0x%llx-0x%llx, requested 0x%x, got
0x%x\n",
+		retval = is_new_memtype_allowed(phys_addr, size, pcm,
new_pcm);
+		pr_err(
+		    "ioremap %s for 0x%llx-0x%llx, requested 0x%x, got
0x%x\n",
+				retval ? "warning" : "error",
 				(unsigned long long)phys_addr,
 				(unsigned long long)(phys_addr +
size),
 				pcm, new_pcm);

This doesn't really make it humanly consumable, a pcm_to_str may help,
such use already exists but not generalized see pat_get_cache_mode().

OK, I will add a pcm_to_str.

quoted

+		if (!retval)
 			goto err_free_memtype;
-		}
+
 		pcm = new_pcm;
 	}

In the future we may be able to proactively hunt for these invalid uses
semantically but to do so we need first a demo driver with all known
possible bugs we can think of.

Right.

Thanks,
-Toshi