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Re: [Qemu-devel] [PATCH v2 2/2] spapr_pci: make index property mandatory
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From: |
Greg Kurz |
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Subject: |
Re: [Qemu-devel] [PATCH v2 2/2] spapr_pci: make index property mandatory |
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Date: |
Tue, 19 Sep 2017 16:03:57 +0200 |
On Tue, 19 Sep 2017 09:03:58 +1000
David Gibson <address@hidden> wrote:
> On Thu, Sep 14, 2017 at 04:14:44PM +0200, Greg Kurz wrote:
> > Creating several PHBs without index property confuses the DRC code
> > and causes issues:
> > - only the first index-less PHB is functional, the other ones will
> > silently ignore hotplugging of PCI devices
> > - QEMU will even terminate if these PHBs have cold-plugged devices
>
> So, this is true, but it's kind of missing the point; we could fix
> those things if we wanted. The real point here is that the non-index
> option is more trouble than it's worth: it's difficult to use, keeps
> requiring (potentially incompatible) changes when some new parameter
> needs adding, and is awkward to check for collisions.
>
Ok, I'll rewrite the changelog accordingly in the next spin.
> > qemu-system-ppc64: -device virtio-net,bus=pci2.0: an attached device
> > is still awaiting release
> >
> > This happens because DR connectors for child PCI devices are created
> > with a DRC index that is derived from the PHB's index property. If the
> > PHBs are created without index, then the same value of -1 is used to
> > compute the DRC indexes for both PHBs, hence causing the collision.
> >
> > Also, the index property is used to compute the placement of the PHB's
> > memory regions. It is limited to 31 or 255, depending on the machine
> > type version. This fits well with the requirements of DRC indexes, which
> > need the PHB index to be a 16-bit value.
> >
> > This patch hence makes the index property mandatory. As a consequence,
> > the PHB's memory regions and BUID are now always configured according
> > to the index, and it is no longer possible to set them from the command
> > line. We have to introduce a PHB instance init function to initialize
> > the 64-bit window address to -1 because pseries-2.7 and older machines
> > don't set it.
> >
> > This DOES BREAK backwards compat, but we don't think the non-index
> > PHB feature was used in practice (at least libvirt doesn't) and the
> > simplification is worth it.
> >
> > Signed-off-by: Greg Kurz <address@hidden>
> > ---
> > v1->v2: - error out if mem64_win_pciaddr is set but mem64_win_size
> > isn't
> > - set mem64_win_addr to -1 for old configuration with 32-bit
> > window below 2G in spapr_phb_realize()
> > - drop instance init function
> >
> > RFC->v1: - as suggested dy David, updated the changelog to explicitely
> > mention that we intentionally break backwards compat.
> > ---
> > hw/ppc/spapr_pci.c | 53
> > +++++++++++-----------------------------------------
> > 1 file changed, 11 insertions(+), 42 deletions(-)
> >
> > diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> > index cf54160526fa..024638e18b53 100644
> > --- a/hw/ppc/spapr_pci.c
> > +++ b/hw/ppc/spapr_pci.c
> > @@ -1523,16 +1523,6 @@ static void spapr_phb_realize(DeviceState *dev,
> > Error **errp)
> > sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
> > Error *local_err = NULL;
> >
> > - if ((sphb->buid != (uint64_t)-1) || (sphb->dma_liobn[0] !=
> > (uint32_t)-1)
> > - || (sphb->dma_liobn[1] != (uint32_t)-1 && windows_supported ==
> > 2)
> > - || (sphb->mem_win_addr != (hwaddr)-1)
> > - || (sphb->mem64_win_addr != (hwaddr)-1)
> > - || (sphb->io_win_addr != (hwaddr)-1)) {
> > - error_setg(errp, "Either \"index\" or other parameters must"
> > - " be specified for PAPR PHB, not both");
> > - return;
> > - }
> > -
> > smc->phb_placement(spapr, sphb->index,
> > &sphb->buid, &sphb->io_win_addr,
> > &sphb->mem_win_addr, &sphb->mem64_win_addr,
> > @@ -1541,36 +1531,12 @@ static void spapr_phb_realize(DeviceState *dev,
> > Error **errp)
> > error_propagate(errp, local_err);
> > return;
> > }
> > - }
> > -
> > - if (sphb->buid == (uint64_t)-1) {
> > - error_setg(errp, "BUID not specified for PHB");
> > - return;
> > - }
> > -
> > - if ((sphb->dma_liobn[0] == (uint32_t)-1) ||
> > - ((sphb->dma_liobn[1] == (uint32_t)-1) && (windows_supported > 1)))
> > {
> > - error_setg(errp, "LIOBN(s) not specified for PHB");
> > - return;
> > - }
> > -
> > - if (sphb->mem_win_addr == (hwaddr)-1) {
> > - error_setg(errp, "Memory window address not specified for PHB");
> > - return;
> > - }
> > -
> > - if (sphb->io_win_addr == (hwaddr)-1) {
> > - error_setg(errp, "IO window address not specified for PHB");
> > + } else {
> > + error_setg(errp, "\"index\" for PAPR PHB is mandatory");
> > return;
> > }
> >
> > if (sphb->mem64_win_size != 0) {
> > - if (sphb->mem64_win_addr == (hwaddr)-1) {
> > - error_setg(errp,
> > - "64-bit memory window address not specified for
> > PHB");
> > - return;
> > - }
> > -
> > if (sphb->mem_win_size > SPAPR_PCI_MEM32_WIN_SIZE) {
> > error_setg(errp, "32-bit memory window of size 0x%"HWADDR_PRIx
> > " (max 2 GiB)", sphb->mem_win_size);
>
> Some of these checks could probably just become assert()s now, where
> they're things determined by the placement code and no longer have
> parameters, a problem indicates a bug in the machine rather than a
> user error.
>
All the *_size properties are still user settable, as before... should we
make them internal and have the placement hook initialize them instead ?
> > @@ -1581,6 +1547,9 @@ static void spapr_phb_realize(DeviceState *dev, Error
> > **errp)
> > /* 64-bit window defaults to identity mapping */
> > sphb->mem64_win_pciaddr = sphb->mem64_win_addr;
> > }
> > + } else if (sphb->mem64_win_pciaddr != (hwaddr) -1) {
> > + error_setg(errp, "64-bit memory window requires
> > \"mem64_win_size\"");
> > + return;
>
> Likewise this new one.
>
mem64_win_pciaddr is still user settable as well...
> > } else if (sphb->mem_win_size > SPAPR_PCI_MEM32_WIN_SIZE) {
> > /*
> > * For compatibility with old configuration, if no 64-bit MMIO
> > @@ -1594,6 +1563,12 @@ static void spapr_phb_realize(DeviceState *dev,
> > Error **errp)
> > sphb->mem64_win_pciaddr =
> > SPAPR_PCI_MEM_WIN_BUS_OFFSET + SPAPR_PCI_MEM32_WIN_SIZE;
> > sphb->mem_win_size = SPAPR_PCI_MEM32_WIN_SIZE;
> > + } else {
> > + /* Old configuration with the 32-bit MMIO window <= 2GiB don't
> > need a
> > + * 64-bit MMIO window.
> > + */
>
> Wouldn't it be easier to just change the test below to check for size
> != 0 instead of checking for addr != -1 as it does now.
>
Yeah indeed.
> > + sphb->mem64_win_addr = (hwaddr) -1;
> > + sphb->mem64_win_pciaddr = (hwaddr) -1;
> > }
> >
> > if (spapr_pci_find_phb(spapr, sphb->buid)) {
> > @@ -1789,18 +1764,12 @@ static void spapr_phb_reset(DeviceState *qdev)
> >
> > static Property spapr_phb_properties[] = {
> > DEFINE_PROP_UINT32("index", sPAPRPHBState, index, -1),
> > - DEFINE_PROP_UINT64("buid", sPAPRPHBState, buid, -1),
> > - DEFINE_PROP_UINT32("liobn", sPAPRPHBState, dma_liobn[0], -1),
> > - DEFINE_PROP_UINT32("liobn64", sPAPRPHBState, dma_liobn[1], -1),
> > - DEFINE_PROP_UINT64("mem_win_addr", sPAPRPHBState, mem_win_addr, -1),
> > DEFINE_PROP_UINT64("mem_win_size", sPAPRPHBState, mem_win_size,
> > SPAPR_PCI_MEM32_WIN_SIZE),
> > - DEFINE_PROP_UINT64("mem64_win_addr", sPAPRPHBState, mem64_win_addr,
> > -1),
> > DEFINE_PROP_UINT64("mem64_win_size", sPAPRPHBState, mem64_win_size,
> > SPAPR_PCI_MEM64_WIN_SIZE),
> > DEFINE_PROP_UINT64("mem64_win_pciaddr", sPAPRPHBState,
> > mem64_win_pciaddr,
> > -1),
> > - DEFINE_PROP_UINT64("io_win_addr", sPAPRPHBState, io_win_addr, -1),
> > DEFINE_PROP_UINT64("io_win_size", sPAPRPHBState, io_win_size,
> > SPAPR_PCI_IO_WIN_SIZE),
> > DEFINE_PROP_BOOL("dynamic-reconfiguration", sPAPRPHBState, dr_enabled,
> >
>
--
Gregory Kurz address@hidden
address@hidden
Software Engineer @ IBM/LTC http://www.ibm.com
Tel 33-5-6218-1607
"Anarchy is about taking complete responsibility for yourself."
Alan Moore.
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