From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michael Ellerman <mpe@ellerman.id.au>
Date: Wed, 27 May 2020 03:48:23 +0000
Subject: Re: [PATCH v3] powerpc/XIVE: SVM: share the event-queue page with the Hypervisor.
Message-Id: <87r1v6domw.fsf@mpe.ellerman.id.au>
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To: Ram Pai <linuxram@us.ibm.com>, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Cc: aik@ozlabs.ru, andmike@linux.ibm.com, groug@kaod.org, clg@kaod.org, sukadev@linux.vnet.ibm.com, bauerman@linux.ibm.com, david@gibson.dropbear.id.au

Ram Pai <linuxram@us.ibm.com> writes:
> XIVE interrupt controller uses an Event Queue (EQ) to enqueue event
> notifications when an exception occurs. The EQ is a single memory page
> provided by the O/S defining a circular buffer, one per server and
> priority couple.
>
> On baremetal, the EQ page is configured with an OPAL call. On pseries,
> an extra hop is necessary and the guest OS uses the hcall
> H_INT_SET_QUEUE_CONFIG to configure the XIVE interrupt controller.
>
> The XIVE controller being Hypervisor privileged, it will not be allowed
> to enqueue event notifications for a Secure VM unless the EQ pages are
> shared by the Secure VM.
>
> Hypervisor/Ultravisor still requires support for the TIMA and ESB page
> fault handlers. Until this is complete, QEMU can use the emulated XIVE
> device for Secure VMs, option "kernel_irqchip=off" on the QEMU pseries
> machine.
>
> Cc: kvm-ppc@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com>
> Cc: Michael Anderson <andmike@linux.ibm.com>
> Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
> Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
> Cc: Paul Mackerras <paulus@ozlabs.org>
> Cc: David Gibson <david@gibson.dropbear.id.au>
> Reviewed-by: Cedric Le Goater <clg@kaod.org>
> Reviewed-by: Greg Kurz <groug@kaod.org>
> Signed-off-by: Ram Pai <linuxram@us.ibm.com>
>
> v3: fix a minor semantics in description.
>     and added reviewed-by from Cedric and Greg.
> v2: better description of the patch from Cedric.
> ---

Please put the change history after the '---' break in future please, I
had to fix this up manually.

cheers