[PATCH] msix: revoke correct amount of msi-x related iomem

[PATCH] msix: revoke correct amount of msi-x related iomem

[Espen Skoglund]

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Calculation of MSI-X table size needs to be masked.

Signed-off-by: Espen Skoglund <espen.skoglund@netronome.com>



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diff -r 25d5dce58729 tools/python/xen/util/pci.py
--- a/tools/python/xen/util/pci.py	Fri May 02 14:38:06 2008 +0100
+++ b/tools/python/xen/util/pci.py	Fri May 02 19:08:45 2008 +0100
@@ -30,6 +30,7 @@
 PCI_STATUS_OFFSET = 0x6
 PCI_CAP_OFFSET = 0x34
 MSIX_BIR_MASK = 0x7
+MSIX_SIZE_MASK = 0x3ff
 
 #Calculate PAGE_SHIFT: number of bits to shift an address to get the page number
 PAGE_SIZE = resource.getpagesize()
@@ -120,8 +121,9 @@
                         message_cont_lo = ord(conf_file.read(1))
                         message_cont_hi = ord(conf_file.read(1))
                         self.msix=1
-                        self.msix_entries = message_cont_lo + \
-                                            message_cont_hi << 8
+                        self.msix_entries = (message_cont_lo + \
+                                             message_cont_hi << 8) \
+                                             & MSIX_SIZE_MASK
                         t_off=conf_file.read(4)
                         p_off=conf_file.read(4)
                         self.table_offset=ord(t_off[0]) | (ord(t_off[1])<<8) | \

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Re: [PATCH] msix: revoke correct amount of msi-x related iomem

[Neil Turton]

Espen Skoglund wrote:
> +                        self.msix_entries = (message_cont_lo + \
> +                                             message_cont_hi << 8) \
> +                                             & MSIX_SIZE_MASK

That still doesn't look right to me since "+" binds tighter than "<<".
I think it needs some more parentheses around "message_cont_hi << 8", at
least if I've understood what the code's supposed to do.

Cheers, Neil.

Re: [PATCH] msix: revoke correct amount of msi-x related iomem

[Espen Skoglund]

Very true.  Not being all that experienced with Python I simply
believed that the previous code was correct.  Checking the reference
manual now I do see that the '<<' operator does indeed precedence over
'+'.  Also, the table size field is actually 11 bits rather than 10.
MSIX_SIZE_MASK should therefore be 0x7ff.

	eSk


[Neil Turton]
> Espen Skoglund wrote:
>> +                        self.msix_entries = (message_cont_lo + \
>> +                                             message_cont_hi << 8) \
>> +                                             & MSIX_SIZE_MASK

> That still doesn't look right to me since "+" binds tighter than
> "<<".  I think it needs some more parentheses around
> "message_cont_hi << 8", at least if I've understood what the code's
> supposed to do.