On 23.05.14 13:55, Gavin Shan wrote:

On Fri, May 23, 2014 at 11:58:22AM +0200, Alexander Graf wrote:

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On 23.05.14 09:37, Gavin Shan wrote:

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On Fri, May 23, 2014 at 08:55:15AM +0200, Alexander Graf wrote:

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Am 23.05.2014 um 06:37 schrieb Gavin Shan [off-list ref]:

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On Thu, May 22, 2014 at 09:10:53PM -0600, Alex Williamson wrote:

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On Thu, 2014-05-22 at 18:23 +1000, Gavin Shan wrote:
The patch adds new IOCTL commands for VFIO PCI device to support
EEH functionality for PCI devices, which have been passed through
from host to somebody else via VFIO.

.../...

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+
+/*
+ * Reset is the major step to recover problematic PE. The following
+ * command helps on that.
+ */
+struct vfio_eeh_pe_reset {
+    __u32 argsz;
+    __u32 option;
+};
+
+#define VFIO_EEH_PE_RESET        _IO(VFIO_TYPE, VFIO_BASE + 24)
+
+/*
+ * One of the steps for recovery after PE reset is to configure the
+ * PCI bridges affected by the PE reset.
+ */
+#define VFIO_EEH_PE_CONFIGURE        _IO(VFIO_TYPE, VFIO_BASE + 25)

What can the user do differently by making these separate ioctls?

hrm, I didn't understood as well. Alex.G could have the explaination.

Alex raised the same concern as me: why separate reset and configure? When we want to recover a device, we need a reset call anyway, right?

Ok. With current ioctl commands, "reset+configure" is required to do
error recovery. Before the recovery, we also need call "configure"
in order to retrieve error log correctly.

Well, the "configure" ioctl (which is a really bad name for what it
does btw) currently only restores the BARs which doesn't sound like
error log retrieval to me.

Could you please suggest a better name? I had VFIO_EEH_PE_CONFIGURE because
it's for RTAS call "ibm,configure-pe".

VFIO_RESTORE_BARS maybe?

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Also, they corresponds to 2 separate RTAS services: "ibm,set-slot-reset"
and "ibm,configure-pe".

Does a guest always issue both? What's the order it calls them in?

For one error, the following RTAS calls was called in general:

< stop device drivers, no PCI traffic expected during recovery >
ibm,set-eeh-option
ibm,configure-pe
< error log retrival >

I see. So the guest retrieves the log via BARs from the device? I guess 
I'm failing to see what "the log" is.


Alex

ibm,set-slot-reset
ibm,read-slot-reset-state2
ibm,configure-pe
< resume device drivers >

We have other scenario. For example, PE reset failure and collect
the permanent log. Prior to that, "ibm,configure-pe" should be called.

Thanks,
Gavin

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Alex