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From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To: Maciej Wieczor-Retman <m.wieczorretman@pm.me>
Cc: tglx@kernel.org, peterz@infradead.org, xin@zytor.com,
	maciej.wieczor-retman@intel.com, babu.moger@amd.com,
	chang.seok.bae@intel.com, sohil.mehta@intel.com,
	dave.hansen@linux.intel.com, jpoimboe@kernel.org,
	elena.reshetova@intel.com, hpa@zytor.com, ak@linux.intel.com,
	darwi@linutronix.de, bp@alien8.de, mingo@redhat.com,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v11 3/4] x86/cpu: Do a sanity check on required feature bits
Date: Thu, 26 Mar 2026 12:04:30 -0700	[thread overview]
Message-ID: <20260326190430.i4dt2dxqpfzwlhcc@desk> (raw)
In-Reply-To: <acV8fbZlkfrrej0k@wieczorr-mobl1.localdomain>

On Thu, Mar 26, 2026 at 06:36:15PM +0000, Maciej Wieczor-Retman wrote:
> >Do we need 2 loops? Can this be simplified as below:
> >
> >static void verify_required_features(const struct cpuinfo_x86 *c)
> >{
> >	u32 required_features[NCAPINTS + 1] = REQUIRED_MASK_INIT;
> >	char cap_buf[X86_CAP_BUF_SIZE];
> >	int i, error = 0;
> 
> Isn't this [NCAPINTS + 1] still a problem because for_each_set_bit() works in 64
> bit chunks? If NCAPINTS becomes an odd number in the future, the
> required_features[] last 32 bits will be uninitialized - REQUIRED_MASK_INIT is
> of (NCAPINTS * sizeof(u32)) size. So they might have some bits set and trigger
> the pr_warn() below.

Isn't a partially initialized array always zeroed out for the uninitialized
part?

  reply	other threads:[~2026-03-26 19:04 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-20 12:50 [PATCH v11 0/4] x86: Capability bits fix and required bits sanity check Maciej Wieczor-Retman
2026-03-20 12:50 ` [PATCH v11 1/4] x86/cpu: Clear feature bits disabled at compile-time Maciej Wieczor-Retman
2026-03-20 12:50 ` [PATCH v11 2/4] x86/cpu: Check if feature string is non-zero Maciej Wieczor-Retman
2026-03-23 14:24   ` Borislav Petkov
2026-03-23 15:52     ` Maciej Wieczor-Retman
2026-03-23 16:23       ` Borislav Petkov
2026-03-23 16:58         ` Maciej Wieczor-Retman
2026-03-23 17:51           ` Borislav Petkov
2026-03-23 18:11             ` Maciej Wieczor-Retman
2026-03-23 18:15               ` H. Peter Anvin
2026-03-20 12:50 ` [PATCH v11 3/4] x86/cpu: Do a sanity check on required feature bits Maciej Wieczor-Retman
2026-03-21  0:31   ` Pawan Gupta
2026-03-21  5:58     ` Maciej Wieczór-Retman
2026-03-23 18:16       ` Pawan Gupta
2026-03-23 18:33         ` Maciej Wieczor-Retman
2026-03-26 18:36     ` Maciej Wieczor-Retman
2026-03-26 19:04       ` Pawan Gupta [this message]
2026-03-26 19:11         ` Maciej Wieczor-Retman
2026-03-28  1:52           ` H. Peter Anvin
2026-03-28  2:01             ` H. Peter Anvin
2026-03-30  9:47               ` Maciej Wieczor-Retman
2026-03-30 10:09             ` Maciej Wieczor-Retman
2026-03-30 16:01               ` Pawan Gupta
2026-03-30 21:24               ` David Laight
2026-03-31  8:12                 ` Maciej Wieczor-Retman
2026-03-31 13:29             ` Maciej Wieczor-Retman
2026-03-23 16:31   ` Borislav Petkov
2026-03-23 17:05     ` Maciej Wieczor-Retman
2026-03-23 17:55       ` Borislav Petkov
2026-03-23 18:43         ` H. Peter Anvin
2026-03-23 18:43     ` H. Peter Anvin
2026-03-23 19:19       ` Borislav Petkov
2026-03-23 20:24         ` H. Peter Anvin
2026-03-23 20:58           ` Borislav Petkov
2026-03-23 21:40             ` H. Peter Anvin
2026-03-23 21:50               ` Borislav Petkov
2026-03-23 21:56                 ` Borislav Petkov
2026-03-23 22:03                 ` H. Peter Anvin
2026-03-23 22:09                   ` Borislav Petkov
2026-03-24  1:16                     ` H. Peter Anvin
2026-03-20 12:50 ` [PATCH v11 4/4] x86/cpu: Clear feature bits whose dependencies were cleared Maciej Wieczor-Retman
2026-03-23 16:35   ` Borislav Petkov
2026-03-23 17:23     ` Maciej Wieczor-Retman
2026-03-23 17:59       ` Borislav Petkov
2026-03-23 18:18         ` Maciej Wieczor-Retman
2026-03-23 18:57         ` H. Peter Anvin
2026-03-23 19:30           ` Borislav Petkov
2026-03-25  9:33             ` Maciej Wieczor-Retman
2026-03-23 19:33           ` Ahmed S. Darwish

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