KVM ARM Archive on lore.kernel.org
 help / color / Atom feed
From: Julien Grall <julien.grall@arm.com>
To: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Cc: marc.zyngier@arm.com, catalin.marinas@arm.com,
	will.deacon@arm.com, Julien Grall <julien.grall@arm.com>
Subject: [PATCH RFC 06/14] arm64/mm: Store the number of asid allocated per context
Date: Thu, 21 Mar 2019 16:36:15 +0000
Message-ID: <20190321163623.20219-7-julien.grall@arm.com> (raw)
In-Reply-To: <20190321163623.20219-1-julien.grall@arm.com>

Currently the number of ASID allocated per context is determined at
compilation time. As the algorithm is becoming generic, the user may
want to instantiate the ASID allocator multiple time with different
number of ASID allocated.

Add a field in asid_info to track the number ASID allocated per context.
This is stored in term of shift amount to avoid division in the code.

This means the number of ASID allocated per context should be a power of
two.

At the same time rename NUM_USERS_ASIDS to NUM_CTXT_ASIDS to make the
name more generic.

Signed-off-by: Julien Grall <julien.grall@arm.com>
---
 arch/arm64/mm/context.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 488845c39c39..5a4c2b1aac71 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -37,6 +37,8 @@ struct asid_info
 	raw_spinlock_t		lock;
 	/* Which CPU requires context flush on next call */
 	cpumask_t		flush_pending;
+	/* Number of ASID allocated by context (shift value) */
+	unsigned int		ctxt_shift;
 } asid_info;
 
 #define active_asid(info, cpu)	*per_cpu_ptr((info)->active, cpu)
@@ -49,15 +51,15 @@ static DEFINE_PER_CPU(u64, reserved_asids);
 #define ASID_FIRST_VERSION(info)	(1UL << ((info)->bits))
 
 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
-#define NUM_USER_ASIDS(info)		(ASID_FIRST_VERSION(info) >> 1)
-#define asid2idx(info, asid)		(((asid) & ~ASID_MASK(info)) >> 1)
-#define idx2asid(info, idx)		(((idx) << 1) & ~ASID_MASK(info))
+#define ASID_PER_CONTEXT		2
 #else
-#define NUM_USER_ASIDS(info)		(ASID_FIRST_VERSION(info))
-#define asid2idx(info, asid)		((asid) & ~ASID_MASK(info))
-#define idx2asid(info, idx)		asid2idx(info, idx)
+#define ASID_PER_CONTEXT		1
 #endif
 
+#define NUM_CTXT_ASIDS(info)		(ASID_FIRST_VERSION(info) >> (info)->ctxt_shift)
+#define asid2idx(info, asid)		(((asid) & ~ASID_MASK(info)) >> (info)->ctxt_shift)
+#define idx2asid(info, idx)		(((idx) << (info)->ctxt_shift) & ~ASID_MASK(info))
+
 /* Get the ASIDBits supported by the current CPU */
 static u32 get_cpu_asid_bits(void)
 {
@@ -102,7 +104,7 @@ static void flush_context(struct asid_info *info)
 	u64 asid;
 
 	/* Update the list of reserved ASIDs and the ASID bitmap. */
-	bitmap_clear(info->map, 0, NUM_USER_ASIDS(info));
+	bitmap_clear(info->map, 0, NUM_CTXT_ASIDS(info));
 
 	for_each_possible_cpu(i) {
 		asid = atomic64_xchg_relaxed(&active_asid(info, i), 0);
@@ -182,8 +184,8 @@ static u64 new_context(struct asid_info *info, atomic64_t *pasid)
 	 * a reserved TTBR0 for the init_mm and we allocate ASIDs in even/odd
 	 * pairs.
 	 */
-	asid = find_next_zero_bit(info->map, NUM_USER_ASIDS(info), cur_idx);
-	if (asid != NUM_USER_ASIDS(info))
+	asid = find_next_zero_bit(info->map, NUM_CTXT_ASIDS(info), cur_idx);
+	if (asid != NUM_CTXT_ASIDS(info))
 		goto set_asid;
 
 	/* We're out of ASIDs, so increment the global generation count */
@@ -192,7 +194,7 @@ static u64 new_context(struct asid_info *info, atomic64_t *pasid)
 	flush_context(info);
 
 	/* We have more ASIDs than CPUs, so this will always succeed */
-	asid = find_next_zero_bit(info->map, NUM_USER_ASIDS(info), 1);
+	asid = find_next_zero_bit(info->map, NUM_CTXT_ASIDS(info), 1);
 
 set_asid:
 	__set_bit(asid, info->map);
@@ -272,17 +274,18 @@ static int asids_init(void)
 	struct asid_info *info = &asid_info;
 
 	info->bits = get_cpu_asid_bits();
+	info->ctxt_shift = ilog2(ASID_PER_CONTEXT);
 	/*
 	 * Expect allocation after rollover to fail if we don't have at least
 	 * one more ASID than CPUs. ASID #0 is reserved for init_mm.
 	 */
-	WARN_ON(NUM_USER_ASIDS(info) - 1 <= num_possible_cpus());
+	WARN_ON(NUM_CTXT_ASIDS(info) - 1 <= num_possible_cpus());
 	atomic64_set(&info->generation, ASID_FIRST_VERSION(info));
-	info->map = kcalloc(BITS_TO_LONGS(NUM_USER_ASIDS(info)),
+	info->map = kcalloc(BITS_TO_LONGS(NUM_CTXT_ASIDS(info)),
 			    sizeof(*info->map), GFP_KERNEL);
 	if (!info->map)
 		panic("Failed to allocate bitmap for %lu ASIDs\n",
-		      NUM_USER_ASIDS(info));
+		      NUM_CTXT_ASIDS(info));
 
 	info->active = &active_asids;
 	info->reserved = &reserved_asids;
@@ -290,7 +293,7 @@ static int asids_init(void)
 	raw_spin_lock_init(&info->lock);
 
 	pr_info("ASID allocator initialised with %lu entries\n",
-		NUM_USER_ASIDS(info));
+		NUM_CTXT_ASIDS(info));
 	return 0;
 }
 early_initcall(asids_init);
-- 
2.11.0

  parent reply index

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-21 16:36 [PATCH RFC 00/14] kvm/arm: Align the VMID allocation with the arm64 ASID one Julien Grall
2019-03-21 16:36 ` [PATCH RFC 01/14] arm64/mm: Introduce asid_info structure and move asid_generation/asid_map to it Julien Grall
2019-03-21 17:03   ` Suzuki K Poulose
2019-03-21 17:27     ` Julien Grall
2019-03-21 16:36 ` [PATCH RFC 02/14] arm64/mm: Move active_asids and reserved_asids to asid_info Julien Grall
2019-03-21 16:36 ` [PATCH RFC 03/14] arm64/mm: Move bits " Julien Grall
2019-03-21 16:36 ` [PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending " Julien Grall
2019-03-21 16:36 ` [PATCH RFC 05/14] arm64/mm: Remove dependency on MM in new_context Julien Grall
2019-03-21 16:36 ` Julien Grall [this message]
2019-03-21 16:36 ` [PATCH RFC 07/14] arm64/mm: Introduce NUM_ASIDS Julien Grall
2019-03-21 16:36 ` [PATCH RFC 08/14] arm64/mm: Split asid_inits in 2 parts Julien Grall
2019-03-21 16:36 ` [PATCH RFC 09/14] arm64/mm: Split the function check_and_switch_context in 3 parts Julien Grall
2019-03-21 16:36 ` [PATCH RFC 10/14] arm64/mm: Introduce a callback to flush the local context Julien Grall
2019-03-21 16:36 ` [PATCH RFC 11/14] arm64: Move the ASID allocator code in a separate file Julien Grall
2019-06-05 16:56   ` Julien Grall
2019-06-05 20:41     ` Palmer Dabbelt
2019-06-11  1:56       ` Gary Guo
2019-06-19  8:07     ` Guo Ren
2019-06-19  8:54       ` Julien Grall
2019-06-19  9:12         ` Will Deacon
2019-06-19 12:18           ` Guo Ren
2019-06-19 12:39             ` Will Deacon
2019-06-20  9:33               ` Guo Ren
2019-06-24 10:40                 ` Will Deacon
2019-06-25  7:25                   ` Palmer Dabbelt
2019-09-07 23:52                   ` Guo Ren
2019-09-12 14:02                     ` Will Deacon
2019-09-12 14:59                       ` Guo Ren
2019-09-13  7:13                         ` Guo Ren
2019-09-14  8:49                           ` Guo Ren
2019-09-16 12:57                           ` Jean-Philippe Brucker
2019-09-19 13:07                             ` Guo Ren
2019-09-19 15:18                               ` Jean-Philippe Brucker
2019-09-20  0:07                                 ` Guo Ren
2019-09-20  7:18                                   ` Jean-Philippe Brucker
2019-09-14 14:01                       ` Palmer Dabbelt
2019-09-15  5:03                         ` Anup Patel
2019-09-16 18:18                           ` Will Deacon
2019-09-16 18:28                             ` Palmer Dabbelt
2019-09-17  3:42                             ` Anup Patel
2019-09-19 13:36                               ` Guo Ren
2019-06-19 11:51         ` Guo Ren
2019-06-19 12:52           ` Julien Grall
2019-06-21 14:16           ` Catalin Marinas
2019-06-23 16:35             ` Guo Ren
2019-06-24 10:22               ` Will Deacon
2019-06-27  9:41                 ` qi.fuli
2019-06-27 10:26                   ` Will Deacon
2019-06-24 15:38               ` Catalin Marinas
2019-06-30  4:29                 ` Guo Ren
2019-07-01  9:17                   ` Catalin Marinas
2019-07-16  3:31                     ` Guo Ren
2019-07-22 16:38                       ` Catalin Marinas
2019-03-21 16:36 ` [PATCH RFC 12/14] arm64/lib: asid: Allow user to update the context under the lock Julien Grall
2019-03-21 16:36 ` [PATCH RFC 13/14] arm/kvm: Introduce a new VMID allocator Julien Grall
2019-03-21 16:36 ` [PATCH RFC 14/14] kvm/arm: Align the VMID allocation with the arm64 ASID one Julien Grall

Reply instructions:

You may reply publically 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=20190321163623.20219-7-julien.grall@arm.com \
    --to=julien.grall@arm.com \
    --cc=catalin.marinas@arm.com \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=marc.zyngier@arm.com \
    --cc=will.deacon@arm.com \
    /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

KVM ARM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvmarm/0 kvmarm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvmarm kvmarm/ https://lore.kernel.org/kvmarm \
		kvmarm@lists.cs.columbia.edu kvmarm@archiver.kernel.org
	public-inbox-index kvmarm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/edu.columbia.cs.lists.kvmarm


AGPL code for this site: git clone https://public-inbox.org/ public-inbox