On 2024/12/16 19:24, Jan Beulich wrote:
> On 13.12.2024 06:42, Jiqian Chen wrote:
>> --- /dev/null
>> +++ b/xen/drivers/vpci/rebar.c
>> @@ -0,0 +1,130 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (C) 2024 Advanced Micro Devices, Inc. All Rights Reserved.
>> + *
>> + * Author: Jiqian Chen <jiqian.c...@amd.com>
>> + */
>> +
>> +#include <xen/hypercall.h>
>> +#include <xen/vpci.h>
>> +
>> +static void cf_check rebar_ctrl_write(const struct pci_dev *pdev,
>> + unsigned int reg,
>> + uint32_t val,
>> + void *data)
>> +{
>> + uint64_t size;
>> + struct vpci_bar *bar = data;
>> +
>> + size = PCI_REBAR_CTRL_SIZE(val);
>> + if ( bar->enabled )
>> + {
>> + if ( size == bar->size )
>> + return;
>> +
>> + /*
>> + * Refuse to resize a BAR while memory decoding is enabled, as
>> + * otherwise the size of the mapped region in the p2m would become
>> + * stale with the newly set BAR size, and the position of the BAR
>> + * would be reset to undefined. Note the PCIe specification also
>> + * forbids resizing a BAR with memory decoding enabled.
>> + */
>> + gprintk(XENLOG_ERR,
>> + "%pp: refuse to resize BAR with memory decoding enabled\n",
>> + &pdev->sbdf);
>> + return;
>> + }
>> +
>> + if ( !((size >> PCI_REBAR_SIZE_BIAS) &
>> + MASK_EXTR(pci_conf_read32(pdev->sbdf,
>> + reg - PCI_REBAR_CTRL + PCI_REBAR_CAP),
>> + PCI_REBAR_CAP_SIZES)) )
>> + gprintk(XENLOG_WARNING,
>> + "%pp: new size %#lx is not supported by hardware\n",
>> + &pdev->sbdf, size);
>
> This only covers the 1Mb ... 128Tb range. What about the 256Tb ... 8Eb one?
Thank you for reminding me!
I will consider that in next version.
>
>> +static int cf_check init_rebar(struct pci_dev *pdev)
>> +{
>> + uint32_t ctrl;
>> + unsigned int rebar_offset, nbars;
>> +
>> + rebar_offset = pci_find_ext_capability(pdev->sbdf,
>> PCI_EXT_CAP_ID_REBAR);
>> +
>> + if ( !rebar_offset )
>> + return 0;
>> +
>> + if ( !is_hardware_domain(pdev->domain) )
>> + {
>> + printk("ReBar is not supported for domUs\n");
>> + return -EOPNOTSUPP;
>> + }
>> +
>> + ctrl = pci_conf_read32(pdev->sbdf, rebar_offset + PCI_REBAR_CTRL);
>> + nbars = MASK_EXTR(ctrl, PCI_REBAR_CTRL_NBAR_MASK);
>> +
>> + for ( unsigned int i = 0; i < nbars; i++, rebar_offset +=
>> PCI_REBAR_CTRL )
>
> PCI_REBAR_CTRL is an offset; it can't be used to bump rebar_offset here.
> That'll need a separate constant, even if both evaluate to 8.
I will add a new macro to represent the '8' in rebar.c
Maybe I can name it "PCI_REBAR_SINGLE_BAR_LEN" ?
>
> Jan
--
Best regards,
Jiqian Chen.
