Re: [Qemu-devel] [PATCH 1/1] Add support for PCI Enhanced Allocation "BARs"

[Stalley, Sean]

Hi Michael,

Have you had a chance to look at this?
There's no hurry, im just curious.

Thanks,
Sean

> -----Original Message-----
> From: Sean O. Stalley [mailto:address@hidden
> Sent: Monday, June 01, 2015 9:38 AM
> To: Michael S. Tsirkin
> Cc: address@hidden
> Subject: Re: [PATCH 1/1] Add support for PCI Enhanced Allocation "BARs"
> 
> On Sun, May 31, 2015 at 08:13:49PM +0200, Michael S. Tsirkin wrote:
> > On Wed, May 13, 2015 at 10:29:42AM -0700, Sean O. Stalley wrote:
> > > On Wed, May 13, 2015 at 08:09:46AM +0200, Michael S. Tsirkin wrote:
> > > > On Tue, May 12, 2015 at 02:23:07PM -0700, Sean O. Stalley wrote:
> > > > > On Tue, May 12, 2015 at 11:33:49AM +0200, Michael S. Tsirkin
> wrote:
> > > > > > On Mon, May 11, 2015 at 01:08:05PM -0700, Sean O. Stalley
> wrote:
> > > > > > > On Mon, May 11, 2015 at 09:26:08PM +0200, Michael S. Tsirkin
> wrote:
> > > > > > > > On Mon, May 11, 2015 at 11:56:44AM -0700, Sean O. Stalley
> wrote:
> > > > > > > > > PCI Enhanced Allocation is a new method of allocating
> > > > > > > > > MMIO & IO resources for PCI devices & bridges. It can be
> > > > > > > > > used instead of the traditional PCI method of using BARs.
> > > > > > > > >
> > > > > > > > > EA entries are hardware-initialized to a fixed address.
> > > > > > > > > Unlike BARs, regions described by EA are cannot be moved.
> > > > > > > > > Because of this, only devices which are perminately
> > > > > > > > > connected to the PCI bus can use EA. A removeable PCI card
> must not use EA.
> > > > > > > > >
> > > > > > > > > This patchset enables any existing QEMU PCI model to use
> > > > > > > > > EA in leiu of BARs. It adds EA options to the PCI device
> paramaters.
> > > > > > > > >
> > > > > > > > > The Enhanced Allocation ECN is publicly available here:
> > > > > > > > > https://www.pcisig.com/specifications/conventional/ECN_E
> > > > > > > > > nhanced_Allocation_23_Oct_2014_Final.pdf
> > > > > > > > >
> > > > > > > > > Signed-off-by: Sean O. Stalley <address@hidden>
> > > > > > > >
> > > > > > > >
> > > > > > > > I will review this, thanks.  Will you also be sending a
> > > > > > > > seabios patch to support these registers?  When you do,
> please Cc me.
> > > > > > >
> > > > > > > Thanks Michael,
> > > > > > >
> > > > > > > I wasn't planning on sending a seabios patch.
> > > > > >
> > > > > > Won't this mean that bios might allocate PCI BARs conflicting
> > > > > > with EA entries, causing guest to crash?
> > > > >
> > > > > The short answer is yes, having EA hardware without an EA-aware
> bios could cause the guest to crash.
> > > > >
> > > > > To make matters worse, EA may cause old OSes may crash as well.
> > > > > If the OS supports hot-swap, and tries to remap the BARs, it could
> have the same problem.
> > > >
> > > > Should _CRS in ACPI be updated to exclude the EA regions?
> > > > If we do this, this problem will go away, won't it?
> > > >
> > >
> > > I think that would work, assuming the OS uses the _CRS.
> > > (https://lwn.net/Articles/373551/)
> > >
> > > I wasn't quite sure how EA should affect ACPI.
> > > This is why I pushed out the QEMU hardware changes before the EDKII
> changes.
> >
> >
> > So I'm waiting for v2 of this?
> >
> 
> I wasn't planning on changing the hardware models in this patch (at least
> not until they are reviewed).
> 
> Based on our discussion about ACPI, I was going to make changes to the
> firmware patches.
> I don't think I need to change anything in this patchset to fix ACPI.
> 
> > > > >
> > > > > This patch allows the user to add EA devices to an existing
> > > > > machine, which is something that would never happen with real EA
> hardware.
> > > > >
> > > > > EA devices will only be present on new platforms.
> > > > > Because of this, I thought it made more sense to add EA support to
> EDKII than to seabios.
> > > > > Will adding EA support to seabios be necessary as well?
> > > >
> > > > If the problem with old OSes is fixable, then I think it's a good idea.
> > > >
> > > > > > > I do have some EDKII/OVMF patches I hope to send out soon. I
> will Cc you on those.
> > > > > > >
> > > > > > > -Sean
> > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > > ---
> > > > > > > > >  hw/pci/Makefile.objs      |   2 +-
> > > > > > > > >  hw/pci/pci.c              |  96 ++++++++++++++++------
> > > > > > > > >  hw/pci/pci_ea.c           | 203
> ++++++++++++++++++++++++++++++++++++++++++++++
> > > > > > > > >  include/hw/pci/pci.h      |   7 ++
> > > > > > > > >  include/hw/pci/pci_ea.h   |  39 +++++++++
> > > > > > > > >  include/hw/pci/pci_regs.h |   4 +
> > > > > > > > >  include/qemu/typedefs.h   |   1 +
> > > > > > > > >  7 files changed, 328 insertions(+), 24 deletions(-)
> > > > > > > > > create mode 100644 hw/pci/pci_ea.c  create mode 100644
> > > > > > > > > include/hw/pci/pci_ea.h