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Mon, 09 Dec 2024 05:59:39 -0800 (PST) Message-ID: <4e4df0ee-67f6-41e3-bfc7-e78011680015@suse.com> Date: Mon, 9 Dec 2024 14:59:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/1] vpci: Add resizable bar support To: Jiqian Chen Cc: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Andrew Cooper , Julien Grall , Stefano Stabellini , Huang Rui , xen-devel@lists.xenproject.org References: <20241202060956.1124162-1-Jiqian.Chen@amd.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <20241202060956.1124162-1-Jiqian.Chen@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 02.12.2024 07:09, Jiqian Chen wrote: > --- /dev/null > +++ b/xen/drivers/vpci/rebar.c > @@ -0,0 +1,93 @@ > +/* SPDX-License-Identifier: GPL-2.0-or-later */ Was this a deliberate decision? We default to GPL-2.0-only, I think. > +/* > + * Copyright (C) 2024 Advanced Micro Devices, Inc. All Rights Reserved. > + * > + * Author: Jiqian Chen > + */ > + > +#include > +#include > + > +static void cf_check rebar_ctrl_write(const struct pci_dev *pdev, > + unsigned int reg, > + uint32_t val, > + void *data) > +{ > + uint64_t size; > + unsigned int index; > + struct vpci_bar *bars = data; > + > + if ( pci_conf_read16(pdev->sbdf, PCI_COMMAND) & PCI_COMMAND_MEMORY ) > + return; I don't think something like this can go uncommented. I don't think the spec mandates to drop writes in this situation? > + index = pci_conf_read32(pdev->sbdf, reg) & PCI_REBAR_CTRL_BAR_IDX; > + if ( index >= PCI_HEADER_NORMAL_NR_BARS ) > + return; > + > + if ( bars[index].type != VPCI_BAR_MEM64_LO && > + bars[index].type != VPCI_BAR_MEM32 ) > + return; > + > + size = PCI_REBAR_CTRL_SIZE(val); > + if ( !((size >> 20) & > + MASK_EXTR(pci_conf_read32(pdev->sbdf, reg - 4), PCI_REBAR_CAP_SIZES)) ) No such literal 4 please. What I think you mean is reg - PCI_REBAR_CTRL + PCI_REBAR_CAP. Also indentation is off (by 2) here. > + gprintk(XENLOG_WARNING, > + "%pp: new size %#lx for BAR%u isn't supported\n", > + &pdev->sbdf, size, index); > + > + bars[index].size = size; > + bars[index].addr = 0; > + bars[index].guest_addr = 0; > + pci_conf_write32(pdev->sbdf, reg, val); > +} > + > +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; > + > + 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 ) > + { > + int rc; > + > + rc = vpci_add_register(pdev->vpci, vpci_hw_read32, vpci_hw_write32, > + rebar_offset + PCI_REBAR_CAP, 4, NULL); The capability register is r/o aiui. While permitting hwdom to write it is fine, DomU-s shouldn't be permitted doing so, just in case. (An alternative to making handler selection conditional here would be to bail early for the !hwdom case, accompanied by a TODO comment. This would then also address the lack of virtualization of the extended capability chain, as we may not blindly expose all capabilities to DomU-s.) > + if ( rc ) > + { > + printk("%pp: add register for PCI_REBAR_CAP failed (rc=%d)\n", > + &pdev->sbdf, rc); > + break; > + } > + > + rc = vpci_add_register(pdev->vpci, vpci_hw_read32, rebar_ctrl_write, > + rebar_offset + PCI_REBAR_CTRL, 4, > + pdev->vpci->header.bars); > + if ( rc ) > + { > + printk("%pp: add register for PCI_REBAR_CTRL failed %d\n", > + &pdev->sbdf, rc); > + break; Is it correct to keep the other handler installed? After all ... > + } > + } > + > + return 0; ... you - imo sensibly - aren't communicating the error back up (to allow the device to be used without BAR resizing. > @@ -541,6 +542,16 @@ > #define PCI_VNDR_HEADER_REV(x) (((x) >> 16) & 0xf) > #define PCI_VNDR_HEADER_LEN(x) (((x) >> 20) & 0xfff) > > +/* Resizable BARs */ > +#define PCI_REBAR_CAP 4 /* capability register */ > +#define PCI_REBAR_CAP_SIZES 0xFFFFFFF0 /* supported BAR sizes */ Misra demands that this have a U suffix. > +#define PCI_REBAR_CTRL 8 /* control register */ > +#define PCI_REBAR_CTRL_BAR_IDX 0x00000007 /* BAR index */ > +#define PCI_REBAR_CTRL_NBAR_MASK 0x000000E0 /* # of resizable BARs */ > +#define PCI_REBAR_CTRL_BAR_SIZE 0x00001F00 /* BAR size */ > +#define PCI_REBAR_CTRL_SIZE(v) \ > + (1UL << (MASK_EXTR(v, PCI_REBAR_CTRL_BAR_SIZE) + 20)) The literal 20 (appearing here the 2nd time) also wants hiding behind a #define. Jan