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2023 21:51:20 +0000 Date: Mon, 6 Feb 2023 13:51:18 -0800 From: Dan Williams To: Gregory Price , Dan Williams CC: , , , Subject: Re: [PATCH 04/18] cxl/region: Validate region mode vs decoder mode Message-ID: <63e1765622185_e3dae2941f@dwillia2-xfh.jf.intel.com.notmuch> References: <167564534874.847146.5222419648551436750.stgit@dwillia2-xfh.jf.intel.com> <167564537131.847146.9020072654741860107.stgit@dwillia2-xfh.jf.intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: SJ0PR13CA0125.namprd13.prod.outlook.com (2603:10b6:a03:2c6::10) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR11MB8107:EE_|DS0PR11MB7684:EE_ X-MS-Office365-Filtering-Correlation-Id: 4251d29c-3436-437a-21f3-08db088c47fc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 voXtxJ/w xpeueu8COqBuyvPNrUbZUbeTv/lvWkm/yKUxn5UXBoofj/S0U473wx/F6kYQ7VhSon3yeg09O3xEecpKwIjc14Zl/jYfKhmjHFy9hCafHgR00EzMfHF1YiFcgRuz4exGddchlHa+qjLAQpfcZc86k2MyOZAms336qk62F0SPRHsX4taxM+zIcpjfGrmxhtjxD35NlhfkIdfobFGyi8/RgpxGXl4ofMjBO8L7XSG75j7CeFZjN9c+5EAdAv7PXQ021HiSaI6nix1EYxqafhWkHsJpPSw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Gregory Price wrote: > On Sun, Feb 05, 2023 at 05:02:51PM -0800, Dan Williams wrote: > > In preparation for a new region mode, do not, for example, allow > > 'ram' decoders to be assigned to 'pmem' regions and vice versa. > > > > Signed-off-by: Dan Williams > > --- > > drivers/cxl/core/region.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c > > index c9e7f05caa0f..53d6dbe4de6d 100644 > > --- a/drivers/cxl/core/region.c > > +++ b/drivers/cxl/core/region.c > > @@ -1217,6 +1217,12 @@ static int cxl_region_attach(struct cxl_region *cxlr, > > struct cxl_dport *dport; > > int i, rc = -ENXIO; > > > > + if (cxled->mode != cxlr->mode) { > > + dev_dbg(&cxlr->dev, "%s region mode: %d mismatch: %d\n", > > + dev_name(&cxled->cxld.dev), cxlr->mode, cxled->mode); > > + return -EINVAL; > > + } > > + > > if (cxled->mode == CXL_DECODER_DEAD) { > > dev_dbg(&cxlr->dev, "%s dead\n", dev_name(&cxled->cxld.dev)); > > return -ENODEV; > > > > > Maybe a stupid question. It will be entirely possible to "convert" pmem > to "ram" (i.e. just online it as system memory). That's a good question, there are two mechanisms for this: 1/ Use ndctl to assign the resulting pmem namespace to devdax mode and then use dax_kmem to online that persistent memory. 2/ If the CXL device supports partitioning ram vs pmem capacity: tear down the pmem region ('cxl destroy-region ...'), repartition the pmem ('cxl set-partition -t ram ...'), create a new ram region ('cxl create-region ...'). > Are type-3 devices with pmem expected to carry 2 decoders (one ram, 1 > pmem), such that you can create a ram region from pmem, or is it expected > that the pmem decoder will be used for pmem, even if it gets onlined > as volatile? Not sure there are any formal expectations when it comes to number of decoders. > Just asking because depending on how that flushes out, you might > expected a "ram region" to get assigned to a "pmem decoder", unless > you're expecting all pmem-carrying-devices to create 2 decoders per pmem > region depending on how the end user intends to use it. Per 2/ above even with a 1-decoder-device there is a spec-defined mechanism to assign all of the device's capacity to ram.