linux-edac.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Yazen Ghannam <yazen.ghannam@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org,
	mchehab@kernel.org, tony.luck@intel.com,
	Smita.KoralahalliChannabasappa@amd.com
Subject: Re: [PATCH v2 03/31] EDAC/amd64: Don't use naked values for DF registers
Date: Thu, 8 Jul 2021 15:35:17 -0400	[thread overview]
Message-ID: <20210708193517.GA15605@aus-x-yghannam.amd.com> (raw)
In-Reply-To: <YNX0ZLRSLgmm2LiA@zn.tnic>

On Fri, Jun 25, 2021 at 05:21:08PM +0200, Borislav Petkov wrote:
> On Wed, Jun 23, 2021 at 07:19:34PM +0000, Yazen Ghannam wrote:
> > +static struct df_reg df_regs[] = {
> > +	/* D18F0x50 (FabricBlockInstanceInformation3_CS) */
> > +	[FAB_BLK_INST_INFO_3]	=	{0, 0x50},
> > +	/* D18F0x104 (DramHoleControl) */
> > +	[DRAM_HOLE_CTL]		=	{0, 0x104},
> > +	/* D18F0x110 (DramBaseAddress) */
> > +	[DRAM_BASE_ADDR]	=	{0, 0x110},
> > +	/* D18F0x114 (DramLimitAddress) */
> > +	[DRAM_LIMIT_ADDR]	=	{0, 0x114},
> > +	/* D18F0x1B4 (DramOffset) */
> > +	[DRAM_OFFSET]		=	{0, 0x1B4},
> > +	/* D18F1x208 (SystemFabricIdMask) */
> > +	[SYS_FAB_ID_MASK]	=	{1, 0x208},
> > +};
> > +
> >  static int umc_normaddr_to_sysaddr(u64 norm_addr, u16 nid, u8 umc, u64 *sys_addr)
> >  {
> >  	u64 dram_base_addr, dram_limit_addr, dram_hole_base;
> > @@ -1059,8 +1091,9 @@ static int umc_normaddr_to_sysaddr(u64 norm_addr, u16 nid, u8 umc, u64 *sys_addr
> >  	u8 cs_mask, cs_id = 0;
> >  	bool hash_enabled = false;
> >  
> > -	/* Read D18F0x1B4 (DramOffset), check if base 1 is used. */
> > -	if (amd_df_indirect_read(nid, 0, 0x1B4, umc, &tmp))
> > +	struct df_reg reg;
> > +
> > +	if (amd_df_indirect_read(nid, df_regs[DRAM_OFFSET], umc, &tmp))
> >  		goto out_err;
> >  
> >  	/* Remove HiAddrOffset from normalized address, if enabled: */
> > @@ -1073,8 +1106,9 @@ static int umc_normaddr_to_sysaddr(u64 norm_addr, u16 nid, u8 umc, u64 *sys_addr
> >  		}
> >  	}
> >  
> > -	/* Read D18F0x110 (DramBaseAddress). */
> > -	if (amd_df_indirect_read(nid, 0, 0x110 + (8 * base), umc, &tmp))
> > +	reg = df_regs[DRAM_BASE_ADDR];
> > +	reg.offset += base * 8;
> 
> So this looks weird: you have a df_regs[] array of all those different
> DF registers which I'd assume is a read-only thing because, well, those
> func and offset things are immutable, i.e., hw registers offsets etc.
> 
> But then here you go and and modify the offset.
> 
> And that df_regs array is globally visible in the driver and if some
> later functionality decides to use it, it'll see the modified offset.
> 
> IOW, I'd make that array read only (const) and use local vars instead to
> pass down to amd_df_indirect_read().
> 
> And I'm also questioning what the point is for that df_reg thing?
> 
> You have them defined but then you have to change them.
> 
> I.e., you can just as well pass in func and offset separately and be
> done with it.
> 
> But maybe there's something else happening in the patches which comes
> later and which will make me go, ahaa.
>

You're right that the values should be immutable. The changes done here
are only for this pair of base/limit registers. Most of the time we'll
only use 2 pairs (4 registers). But some systems will need to look at 16
pairs, and so this current approach seemed nicer than writing out 32
registers with mostly redundant information.

I was trying to make the code more "self-documenting" and move away from
magic numbers, etc. But it all looks okay to me, so I'm not sure which
way to go (magic numbers + code comments, something else, etc.).

So I'm inclined to stick with passing in the func/offset values and
dropping the df_regs thing.

Thanks,
Yazen


  reply	other threads:[~2021-07-08 19:35 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-23 19:19 [PATCH v2 00/31] AMD MCA Address Translation Updates Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 01/31] x86/MCE/AMD, EDAC/amd64: Move address translation to AMD64 EDAC Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 02/31] x86/amd_nb, EDAC/amd64: Move DF Indirect Read " Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 03/31] EDAC/amd64: Don't use naked values for DF registers Yazen Ghannam
2021-06-25 15:21   ` Borislav Petkov
2021-07-08 19:35     ` Yazen Ghannam [this message]
2021-06-23 19:19 ` [PATCH v2 04/31] EDAC/amd64: Allow for DF Indirect Broadcast reads Yazen Ghannam
2021-06-30 16:22   ` Borislav Petkov
2021-07-08 19:44     ` Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 05/31] EDAC/amd64: Add context struct Yazen Ghannam
2021-06-30 17:17   ` Borislav Petkov
2021-07-08 19:53     ` Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 06/31] EDAC/amd64: Define Data Fabric operations Yazen Ghannam
2021-06-30 17:19   ` Borislav Petkov
2021-07-08 19:55     ` Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 07/31] EDAC/amd64: Define functions for DramOffset Yazen Ghannam
2021-06-30 17:27   ` Borislav Petkov
2021-07-08 20:08     ` Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 08/31] EDAC/amd64: Define function to read DRAM address map registers Yazen Ghannam
2021-06-30 17:29   ` Borislav Petkov
2021-06-23 19:19 ` [PATCH v2 09/31] EDAC/amd64: Define function to find interleaving mode Yazen Ghannam
2021-06-30 17:33   ` Borislav Petkov
2021-07-08 20:09     ` Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 10/31] EDAC/amd64: Define function to denormalize address Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 11/31] EDAC/amd64: Define function to add DRAM base and hole Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 12/31] EDAC/amd64: Define function to dehash address Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 13/31] EDAC/amd64: Define function to check DRAM limit address Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 14/31] EDAC/amd64: Remove goto statements Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 15/31] EDAC/amd64: Simplify function parameters Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 16/31] EDAC/amd64: Define function to get Interleave Address Bit Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 17/31] EDAC/amd64: Skip denormalization if no interleaving Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 18/31] EDAC/amd64: Define function to get number of interleaved channels Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 19/31] EDAC/amd64: Define function to get number of interleaved dies Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 20/31] EDAC/amd64: Define function to get number of interleaved sockets Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 21/31] EDAC/amd64: Remove unnecessary assert Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 22/31] EDAC/amd64: Define function to make space for CS ID Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 23/31] EDAC/amd64: Define function to calculate " Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 24/31] EDAC/amd64: Define function to insert CS ID into address Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 25/31] EDAC/amd64: Define function to get CS Fabric ID Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 26/31] EDAC/amd64: Define function to find shift and mask values Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 27/31] EDAC/amd64: Update CS ID calculation to match reference code Yazen Ghannam
2021-06-23 19:19 ` [PATCH v2 28/31] EDAC/amd64: Match hash function to " Yazen Ghannam
2021-06-23 19:20 ` [PATCH v2 29/31] EDAC/amd64: Define helper function to get interleave address select bit Yazen Ghannam
2021-06-23 19:20 ` [PATCH v2 30/31] EDAC/amd64: Add support for address translation on DF3 systems Yazen Ghannam
2021-06-23 19:20 ` [PATCH v2 31/31] EDAC/amd64: Add glossary of acronyms for address translation Yazen Ghannam

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210708193517.GA15605@aus-x-yghannam.amd.com \
    --to=yazen.ghannam@amd.com \
    --cc=Smita.KoralahalliChannabasappa@amd.com \
    --cc=bp@alien8.de \
    --cc=linux-edac@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mchehab@kernel.org \
    --cc=tony.luck@intel.com \
    --subject='Re: [PATCH v2 03/31] EDAC/amd64: Don'\''t use naked values for DF registers' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).