From: Dan Williams <dan.j.williams@intel.com>
To: Robert Richter <rrichter@amd.com>,
Dan Williams <dan.j.williams@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Ira Weiny <ira.weiny@intel.com>,
Ben Widawsky <bwidawsk@kernel.org>, <linux-cxl@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Len Brown <lenb@kernel.org>,
"Jonathan Cameron" <Jonathan.Cameron@huawei.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Terry Bowman <terry.bowman@amd.com>
Subject: Re: [PATCH v2 06/12] cxl/acpi: Extract component registers of restricted hosts from RCRB
Date: Mon, 24 Oct 2022 14:24:54 -0700 [thread overview]
Message-ID: <635702a652637_4da32941a@dwillia2-xfh.jf.intel.com.notmuch> (raw)
In-Reply-To: <Y1b92DF0c36/QDbo@rric.localdomain>
Robert Richter wrote:
> On 20.10.22 22:17:07, Dan Williams wrote:
> > Robert Richter wrote:
> > > A downstream port must be connected to a component register block.
> > > For restricted hosts the base address is determined from the RCRB. The
> > > RCRB is provided by the host's CEDT CHBS entry. Rework CEDT parser to
> > > get the RCRB and add code to extract the component register block from
> > > it.
> > >
> > > RCRB's BAR[0..1] point to the component block containing CXL subsystem
> > > component registers. MEMBAR extraction follows the PCI base spec here,
> > > esp. 64 bit extraction and memory range alignment (6.0, 7.5.1.2.1).
> > >
> > > Note: Right now the component register block is used for HDM decoder
> > > capability only which is optional for RCDs. If unsupported by the RCD,
> > > the HDM init will fail. It is future work to bypass it in this case.
> > >
> > > Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> > > Signed-off-by: Robert Richter <rrichter@amd.com>
> > > ---
> > > drivers/cxl/acpi.c | 79 ++++++++++++++++++++++++++++++++++++++++------
> > > 1 file changed, 69 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > > index fb9f72813067..a92d5d7b7a92 100644
> > > --- a/drivers/cxl/acpi.c
> > > +++ b/drivers/cxl/acpi.c
> > > @@ -9,6 +9,8 @@
> > > #include "cxlpci.h"
> > > #include "cxl.h"
> > >
> > > +#define CXL_RCRB_SIZE SZ_8K
> > > +
> > > static unsigned long cfmws_to_decoder_flags(int restrictions)
> > > {
> > > unsigned long flags = CXL_DECODER_F_ENABLE;
> > > @@ -229,27 +231,82 @@ static int add_host_bridge_uport(struct device *match, void *arg)
> > > struct cxl_chbs_context {
> > > struct device *dev;
> > > unsigned long long uid;
> > > - resource_size_t chbcr;
> > > + struct acpi_cedt_chbs chbs;
> > > };
> > >
> > > -static int cxl_get_chbcr(union acpi_subtable_headers *header, void *arg,
> > > - const unsigned long end)
> > > +static int cxl_get_chbs(union acpi_subtable_headers *header, void *arg,
> > > + const unsigned long end)
> > > {
> > > struct cxl_chbs_context *ctx = arg;
> > > struct acpi_cedt_chbs *chbs;
> > >
> > > - if (ctx->chbcr)
> > > + if (ctx->chbs.base)
> > > return 0;
> > >
> > > chbs = (struct acpi_cedt_chbs *) header;
> > >
> > > if (ctx->uid != chbs->uid)
> > > return 0;
> > > - ctx->chbcr = chbs->base;
> > > + ctx->chbs = *chbs;
> > >
> > > return 0;
> > > }
> > >
> > > +static resource_size_t cxl_get_chbcr(struct cxl_chbs_context *ctx)
> > > +{
> >
> > The core logic of this looks good, but this wants to be shared with the
> > upstream port component register discovery.
> >
> > Full disclosure I am reconciling these patches with an attempt that Dave
> > Jiang made at this topic. Since your series hit the list first I will
> > let it take the lead, but then fill it in with comments and learnings
> > from Dave's effort.
> >
> > So in this case Dave moved this into the drivers/cxl/core/regs.c with a
> > function signature like:
> >
> > enum cxl_rcrb {
> > CXL_RCRB_DOWNSTREAM,
> > CXL_RCRB_UPSTREAM,
> > };
> >
> > resource_size_t cxl_rcrb_to_component(struct device *dev,
> > resource_size_t rcrb_base, int len,
> > enum cxl_rcrb which);
> >
> > ...where @which alternates when called by cxl_acpi for the downstream
> > case, or cxl_mem for the upstream case.
>
> Ok, I see where to go here. Could you point me to Dave's postings you
> are referring to? I checked linux-cxl and could not find anything
> related to RCRB or that changes regs.c.
He was in the middle of tidying them when you posted your series, but I
think it would not hurt to push them to a git tree so you can grab the
bits and pieces you want.
Dave?
next prev parent reply other threads:[~2022-10-24 23:05 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-18 13:23 [PATCH v2 00/12] cxl: Add support for Restricted CXL hosts (RCD mode) Robert Richter
2022-10-18 13:23 ` [PATCH v2 01/12] cxl/core: Remove duplicate declaration of devm_cxl_iomap_block() Robert Richter
2022-10-20 23:56 ` Dan Williams
2022-10-21 8:54 ` Robert Richter
2022-10-18 13:23 ` [PATCH v2 02/12] cxl/core: Check physical address before mapping it in devm_cxl_iomap_block() Robert Richter
2022-10-21 0:01 ` Dan Williams
2022-10-18 13:23 ` [PATCH v2 03/12] cxl: Unify debug messages when calling devm_cxl_add_port() Robert Richter
2022-10-21 0:20 ` Dan Williams
2022-10-21 8:57 ` Robert Richter
2022-10-18 13:23 ` [PATCH v2 04/12] cxl: Unify debug messages when calling devm_cxl_add_dport() Robert Richter
2022-10-21 0:32 ` Dan Williams
2022-10-21 9:00 ` Robert Richter
2022-10-18 13:23 ` [PATCH v2 05/12] cxl/acpi: Improve debug messages in cxl_acpi_probe() Robert Richter
2022-10-21 1:00 ` Dan Williams
2022-10-18 13:23 ` [PATCH v2 06/12] cxl/acpi: Extract component registers of restricted hosts from RCRB Robert Richter
2022-10-18 13:31 ` Rafael J. Wysocki
2022-10-18 18:41 ` Robert Richter
2022-10-18 18:57 ` Rafael J. Wysocki
2022-10-19 10:46 ` Robert Richter
2022-10-21 5:17 ` Dan Williams
2022-10-24 21:04 ` Robert Richter
2022-10-24 21:24 ` Dan Williams [this message]
2022-10-24 22:37 ` Dan Williams
[not found] ` <63cd195a-f5d0-b016-d833-b3a9c86ff6ee@intel.com>
2022-10-24 23:50 ` Robert Richter
2022-10-24 23:57 ` Dan Williams
2022-10-18 13:23 ` [PATCH v2 07/12] cxl: Remove dev_is_cxl_root_child() check in devm_cxl_enumerate_ports() Robert Richter
2022-10-21 5:38 ` Dan Williams
2022-10-21 6:32 ` Verma, Vishal L
2022-11-09 14:33 ` Robert Richter
2022-10-18 13:23 ` [PATCH v2 08/12] cxl: Factor out code in devm_cxl_enumerate_ports() to find_port_attach_ep() Robert Richter
2022-10-18 13:23 ` [PATCH v2 09/12] cxl: Extend devm_cxl_enumerate_ports() to support restricted devices (RCDs) Robert Richter
2022-10-18 13:23 ` [PATCH v2 10/12] cxl: Do not ignore PCI config read errors in match_add_dports() Robert Richter
2022-10-18 13:23 ` [PATCH v2 11/12] cxl: Factor out code in match_add_dports() to pci_dev_add_dport() Robert Richter
2022-10-18 13:23 ` [PATCH v2 12/12] cxl: Extend devm_cxl_port_enumerate_dports() to support restricted hosts (RCH) Robert Richter
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