On Thu, Jun 06, 2019 at 02:13:20PM +1000, Alexey Kardashevskiy wrote: > I changed my handy scripts for posting patches and the subject line > broke, do I need to repost? It made it to the patchworks though.
No, that's fine I've seen it and will look at it when I have the chance. > > > > On 06/06/2019 14:09, Alexey Kardashevskiy wrote: > > The pseries guests do not normally allocate PCI resouces and rely on > > the system firmware doing so. Furthermore at least at some point in > > the past the pseries guests won't even be allowed to change BARs, probably > > it is still the case for phyp. So since the initial commit we have [1] > > which prevents resource reallocation. > > > > This is not a problem until we want specific BAR alignments, for example, > > PAGE_SIZE==64k to make sure we can still map MMIO BARs directly. For > > the boot time devices we handle this in SLOF [2] but since QEMU's RTAS > > does not allocate BARs, the guest does this instead and does not align > > BARs even if Linux is given pci=resource_alignment=16@pci:0:0 as > > PCI_PROBE_ONLY makes Linux ignore alignment requests. > > > > ARM folks added a dial to control PCI_PROBE_ONLY via the device tree [3]. > > This makes use of the dial to advertise to the guest that we can handle > > BAR reassignments. > > > > We do not remove the flag from [1] as pseries guests are still supported > > under phyp so having that removed may cause problems. > > > > [1] > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/platforms/pseries/setup.c?h=v5.1#n773 > > [2] > > https://git.qemu.org/?p=SLOF.git;a=blob;f=board-qemu/slof/pci-phb.fs;h=06729bcf77a0d4e900c527adcd9befe2a269f65d;hb=HEAD#l338 > > [3] > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f81c11af > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> > > --- > > hw/ppc/spapr.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > > index 6dd8aaac3340..84d16f9edaca 100644 > > --- a/hw/ppc/spapr.c > > +++ b/hw/ppc/spapr.c > > @@ -1209,6 +1209,9 @@ static void spapr_dt_chosen(SpaprMachineState *spapr, > > void *fdt) > > _FDT(fdt_setprop_string(fdt, chosen, "stdout-path", stdout_path)); > > } > > > > + /* We can deal with BAR reallocation just fine, advertise it to the > > guest */ > > + _FDT(fdt_setprop_cell(fdt, chosen, "linux,pci-probe-only", 0)); > > + > > spapr_dt_ov5_platform_support(spapr, fdt, chosen); > > > > g_free(stdout_path); > > > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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