linux-kernel - Re: [RFC PATCH v7 10/12] ACPI:RAS2: Add common library for RAS2 PCC interfaces

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3fa20038-347f-48c3-814c-0dc1ed109244@os.amperecomputing.com>
Date: Thu, 28 Mar 2024 16:40:58 -0700
From: Daniel Ferguson <danielf@...amperecomputing.com>
To: shiju.jose@...wei.com, linux-cxl@...r.kernel.org,
 linux-acpi@...r.kernel.org, linux-mm@...ck.org, dan.j.williams@...el.com,
 dave@...olabs.net, jonathan.cameron@...wei.com, dave.jiang@...el.com,
 alison.schofield@...el.com, vishal.l.verma@...el.com, ira.weiny@...el.com
Cc: linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
 david@...hat.com, Vilas.Sridharan@....com, leo.duran@....com,
 Yazen.Ghannam@....com, rientjes@...gle.com, jiaqiyan@...gle.com,
 tony.luck@...el.com, Jon.Grimm@....com, dave.hansen@...ux.intel.com,
 rafael@...nel.org, lenb@...nel.org, naoya.horiguchi@....com,
 james.morse@....com, jthoughton@...gle.com, somasundaram.a@....com,
 erdemaktas@...gle.com, pgonda@...gle.com, duenwen@...gle.com,
 mike.malvestuto@...el.com, gthelen@...gle.com,
 wschwartz@...erecomputing.com, dferguson@...erecomputing.com,
 tanxiaofei@...wei.com, prime.zeng@...ilicon.com,
 kangkang.shen@...urewei.com, wanghuiqiang@...wei.com, linuxarm@...wei.com,
 wbs@...amperecomputing.com
Subject: Re: [RFC PATCH v7 10/12] ACPI:RAS2: Add common library for RAS2 PCC
 interfaces

> +static int ras2_check_pcc_chan(struct ras2_context *ras2_ctx)
> +{
> +	struct acpi_ras2_shared_memory  __iomem *generic_comm_base = ras2_ctx->pcc_comm_addr;
> +	ktime_t next_deadline = ktime_add(ktime_get(), ras2_ctx->deadline);
> +
> +	while (!ktime_after(ktime_get(), next_deadline)) {
> +		/*
> +		 * As per ACPI spec, the PCC space wil be initialized by
> +		 * platform and should have set the command completion bit when
> +		 * PCC can be used by OSPM
> +		 */
> +		if (readw_relaxed(&generic_comm_base->status) & RAS2_PCC_CMD_COMPLETE)
> +			return 0;

We should consider adding error checking here. In a modification of this
driver in our enabling efforts, we are checking bit 2 in the status register
for errors. For example, in our FW, we will set bit 2 if you try to 
disable an
already disabled scrub.
> +		/*
> +		 * Reducing the bus traffic in case this loop takes longer than
> +		 * a few retries.
> +		 */
> +		udelay(10);
> +	}
> +
> +	return -EIO;
> +}