[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH 4/6] mini-os/x86-64 entry: remove unnecessary event blocking



Sorry about my delayed response. I just got some time to take a look and revise these patches.

It seems to me the bit of %gs manipulation is used for executing "do_hypervisor_callback" on a different stack. After it's done, it switches back to the original stack and resumes from there. The event mask is not touched during this process. I put mini-os under gdb just to verify, and for the runs I observed, event mask remains untouched.

Is there anything I am missing?

On 03/15/2013 03:16 PM, Konrad Rzeszutek Wilk wrote:
On Fri, Mar 08, 2013 at 03:30:17PM -0600, Xu Zhang wrote:
We don't need to block events here because:
  - if we came from "hypervisor_callback", events are disabled at this point,
    no need to block again;
Hm, I think I am not following it. It does a bit of %gs manipulation which
looks to point to the cpu0_pda.irqcount.

?
  - if we came from "error_entry", we shouldn't touch event mask, for
    exception hanlding are meant to be interrupted by Xen events (virtual
handling
    irq).

Signed-off-by: Xu Zhang <xzhang@xxxxxxxxxx>
---
  extras/mini-os/arch/x86/x86_64.S |    1 -
  1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/extras/mini-os/arch/x86/x86_64.S b/extras/mini-os/arch/x86/x86_64.S
index 79e893f..5e0021b 100644
--- a/extras/mini-os/arch/x86/x86_64.S
+++ b/extras/mini-os/arch/x86/x86_64.S
@@ -185,7 +185,6 @@ ENTRY(hypervisor_callback2)
error_exit:
        RESTORE_REST
-       XEN_BLOCK_EVENTS(%rsi)
retint_kernel:
  retint_restore_args:
--
1.7.7.6


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.