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Message-Id: <20221021131204.5581-7-james.morse@arm.com>
Date: Fri, 21 Oct 2022 13:11:52 +0000
From: James Morse <james.morse@....com>
To: x86@...nel.org, linux-kernel@...r.kernel.org
Cc: Fenghua Yu <fenghua.yu@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
H Peter Anvin <hpa@...or.com>,
Babu Moger <Babu.Moger@....com>,
James Morse <james.morse@....com>,
shameerali.kolothum.thodi@...wei.com,
D Scott Phillips OS <scott@...amperecomputing.com>,
carl@...amperecomputing.com, lcherian@...vell.com,
bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
Jamie Iles <quic_jiles@...cinc.com>,
Xin Hao <xhao@...ux.alibaba.com>, xingxin.hx@...nanolis.org,
baolin.wang@...ux.alibaba.com, peternewman@...gle.com
Subject: [PATCH 06/18] x86/resctrl: Allow the allocator to check if a CLOSID can allocate clean RMID
MPAM's PMG bits extend its PARTID space, meaning the same PMG value can be
used for different control groups.
This means once a CLOSID is allocated, all its monitoring ids may still be
dirty, and held in limbo.
Add a helper to allow the CLOSID allocator to check if a CLOSID has dirty
RMID values. This behaviour is enabled by a kconfig option selected by
the architecture, which avoids a pointless search for x86.
Signed-off-by: James Morse <james.morse@....com>
---
arch/x86/kernel/cpu/resctrl/internal.h | 1 +
arch/x86/kernel/cpu/resctrl/monitor.c | 31 ++++++++++++++++++++++++++
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 18 +++++++++------
3 files changed, 43 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index c8c46fe088be..faec12025a58 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -519,6 +519,7 @@ int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp);
void rdtgroup_pseudo_lock_remove(struct rdtgroup *rdtgrp);
struct rdt_domain *get_domain_from_cpu(int cpu, struct rdt_resource *r);
int closids_supported(void);
+bool resctrl_closid_is_dirty(u32 closid);
void closid_free(int closid);
int alloc_rmid(u32 closid);
void free_rmid(u32 closid, u32 rmid);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 59da256a77fe..99854ef4dee4 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -320,6 +320,37 @@ static struct rmid_entry *resctrl_find_free_rmid(u32 closid)
return ERR_PTR(-ENOSPC);
}
+/**
+ * resctrl_closid_is_dirty - Determine if clean RMID can be allocate for this
+ * CLOSID.
+ * @closid: The CLOSID that is being queried.
+ *
+ * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocate CLOSID
+ * may not be able to allocate clean RMID. To avoid this the allocator will
+ * only return clean CLOSID.
+ */
+bool resctrl_closid_is_dirty(u32 closid)
+{
+ struct rmid_entry *entry;
+ int i;
+
+ lockdep_assert_held(&rdtgroup_mutex);
+
+ if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID))
+ return false;
+
+ for (i = 0; i < resctrl_arch_system_num_rmid_idx(); i++) {
+ entry = &rmid_ptrs[i];
+ if (entry->closid != closid)
+ continue;
+
+ if (entry->busy)
+ return true;
+ }
+
+ return false;
+}
+
/*
* As of now the RMIDs allocation is the same in each domain.
* However we keep track of which packages the RMIDs
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index ac88610a6946..59f33adcf6f8 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -93,7 +93,7 @@ void rdt_last_cmd_printf(const char *fmt, ...)
* - Our choices on how to configure each resource become progressively more
* limited as the number of resources grows.
*/
-static int closid_free_map;
+static unsigned long closid_free_map;
static int closid_free_map_len;
int closids_supported(void)
@@ -119,14 +119,18 @@ static void closid_init(void)
static int closid_alloc(void)
{
- u32 closid = ffs(closid_free_map);
+ u32 closid;
- if (closid == 0)
- return -ENOSPC;
- closid--;
- closid_free_map &= ~(1 << closid);
+ for_each_set_bit(closid, &closid_free_map, closid_free_map_len) {
+ if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID) &&
+ resctrl_closid_is_dirty(closid))
+ continue;
- return closid;
+ clear_bit(closid, &closid_free_map);
+ return closid;
+ }
+
+ return -ENOSPC;
}
void closid_free(int closid)
--
2.30.2
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