linux-kernel - [tip: x86/cache] x86/resctrl: Fix allocation of cleanest CLOSID on platforms with no monitors

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] [day] [month] [year] [list]

Message-ID: <174180004175.14745.2700864391580765240.tip-bot2@tip-bot2>
Date: Wed, 12 Mar 2025 17:20:41 -0000
From: "tip-bot2 for James Morse" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: James Morse <james.morse@....com>, "Borislav Petkov (AMD)" <bp@...en8.de>,
 Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
 David Hildenbrand <david@...hat.com>,
 Reinette Chatre <reinette.chatre@...el.com>, Tony Luck <tony.luck@...el.com>,
 Fenghua Yu <fenghuay@...dia.com>, Babu Moger <babu.moger@....com>,
 Carl Worth <carl@...amperecomputing.com>,
 Peter Newman <peternewman@...gle.com>,
 Amit Singh Tomar <amitsinght@...vell.com>,
 Shanker Donthineni <sdonthineni@...dia.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/cache] x86/resctrl: Fix allocation of cleanest CLOSID on
 platforms with no monitors

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     a121798ae669351ec0697c94f71c3a692b2a755b
Gitweb:        https://git.kernel.org/tip/a121798ae669351ec0697c94f71c3a692b2a755b
Author:        James Morse <james.morse@....com>
AuthorDate:    Tue, 11 Mar 2025 18:36:46 
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Wed, 12 Mar 2025 12:21:48 +01:00

x86/resctrl: Fix allocation of cleanest CLOSID on platforms with no monitors

Commit

  6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid")

added logic that causes resctrl to search for the CLOSID with the fewest dirty
cache lines when creating a new control group, if requested by the arch code.
This depends on the values read from the llc_occupancy counters. The logic is
applicable to architectures where the CLOSID effectively forms part of the
monitoring identifier and so do not allow complete freedom to choose an unused
monitoring identifier for a given CLOSID.

This support missed that some platforms may not have these counters.  This
causes a NULL pointer dereference when creating a new control group as the
array was not allocated by dom_data_init().

As this feature isn't necessary on platforms that don't have cache occupancy
monitors, add this to the check that occurs when a new control group is
allocated.

Fixes: 6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid")
Signed-off-by: James Morse <james.morse@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Reviewed-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
Reviewed-by: Fenghua Yu <fenghuay@...dia.com>
Reviewed-by: Babu Moger <babu.moger@....com>
Tested-by: Carl Worth <carl@...amperecomputing.com> # arm64
Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Tested-by: Peter Newman <peternewman@...gle.com>
Tested-by: Amit Singh Tomar <amitsinght@...vell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@...dia.com> # arm64
Tested-by: Babu Moger <babu.moger@....com>
Link: https://lore.kernel.org/r/20250311183715.16445-2-james.morse@arm.com
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 6419e04..04b653d 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -157,7 +157,8 @@ static int closid_alloc(void)
 
 	lockdep_assert_held(&rdtgroup_mutex);
 
-	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {
+	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID) &&
+	    is_llc_occupancy_enabled()) {
 		cleanest_closid = resctrl_find_cleanest_closid();
 		if (cleanest_closid < 0)
 			return cleanest_closid;