Re: [Xen-devel] [PATCH] qemu-xen-trad: free all the pirqs for msi/msix when driver unloads

[Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>]

There is a patch dependency missed.

commit adf74189dd58014744a4b8c9d64407d629da5e2f
Author: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Date:   Mon Dec 10 12:43:33 2012 +0000

    qemu-xen-trad/pt_msi_disable: do not clear all MSI flags

    "qemu-xen-trad: fix msi_translate with PV event delivery" added a
    pt_msi_disable() call into pt_msgctrl_reg_write, clearing the MSI flags
    as a consequence. MSIs get enabled again soon after by calling
    pt_msi_setup.

    However the MSI flags are only setup once in the pt_msgctrl_reg_init
    function, so from the QEMU point of view the device has lost some
    important properties, like for example PCI_MSI_FLAGS_64BIT.

    This patch fixes the bug by clearing only the MSI
    enabled/mapped/initialized flags in pt_msi_disable.

    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
    Tested-by: G.R. <firemeteor@xxxxxxxxxxxxxxxxxxxxx>
    Xen-devel: http://marc.info/?l=xen-devel&m=135489879503075

diff --git a/hw/pt-msi.c b/hw/pt-msi.c
index 73f737d..b03b989 100644
--- a/hw/pt-msi.c
+++ b/hw/pt-msi.c
@@ -213,7 +213,7 @@ void pt_msi_disable(struct pt_dev *dev)

 out:
     /* clear msi info */
-    dev->msi->flags = 0;
+    dev->msi->flags &= ~(MSI_FLAG_UNINIT | PT_MSI_MAPPED | 
PCI_MSI_FLAGS_ENABLE);
     dev->msi->pirq = -1;
     dev->msi_trans_en = 0;
 }

On 2014-7-2 23:06, Ian Jackson wrote:
> Konrad Rzeszutek Wilk writes ("[Xen-devel] [PATCH] qemu-xen-trad: free all the pirqs 
> for msi/msix when driver unloads"):
> > From: Zhenzhong Duan<zhenzhong.duan@xxxxxxxxxx>
> >
> > Pirqs are not freed when driver unloads, then new pirqs are allocated when
> > driver reloads. This could exhaust pirqs if do it in a loop.
> >
> > This patch fixes the bug by freeing pirqs when ENABLE bit is cleared in
> > msi/msix control reg.
> I have backported this to 4.4 and 4.3.  It did not apply cleanly to
> 4.2 (and I have not investgated why).
>
> Thanks,
> Ian.

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