[Xen-ia64-devel] [PATCH] fix oops message from timer_interrupt on VTI domain

[Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>]

Hi,

This patch intends to fix the oops message from timer_interrupt on VTI 
domain. 
This problem occurred when we test PV-on-HVM driver by ltp-20061121.
Typical message shown as follows.

ltp Now Running...( Exception mode )
dom=domVTI
1 times
Unable to find swap-space signature
Oops: timer tick before it's due (itc=ed98bb5849,itm=ed98bb5849)
Oops: timer tick before it's due (itc=f20bca8ca3,itm=f20bca8ca3)
Oops: timer tick before it's due (itc=f4ea4e2b32,itm=f4ea4e2b32)
mmap1(7392): unaligned access to 0x60000fffffffb634, ip=0x200000000004fad0
mmap1(7392): unaligned access to 0x60000fffffffb634, ip=0x200000000004fad0
ltp End


These oops messages are generated
because timer_interrupt checks the condition itc > itm.
Currently Xen-hypervisor outputs following values, 
max(current_itc,vtm->last_itc),
Some occasion, oops message appeared if we use the value of vtm->last_itc as 
ia64_get_itc() return value, because the vtm->last_itc is same as itm.
To fix this issue, it needs to add return value like +1.

But, ia64_get_itc() is handled at vmx_asm_mov_from_ar@xxxxxxxxxxx
and it works same logic of  now_itc()@vlsapic.c.
And these routines shared vtm->last_itc.
So I fix this problem by adding +1 at update_last_itc.

Signed-off-by: Atsushi SAKAI <sakaia@xxxxxxxxxxxxxx>


Thanks
Atsushi SAKAI

Attachment: fix-vti-oops.patch
Description: Binary data

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