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From: Andrii Anisov <andrii.anisov@gmail.com>
Cc: xen-devel@lists.xenproject.org,
	Julien Grall <julien.grall@arm.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Andrii Anisov <andrii_anisov@epam.com>
Subject: [RFC 12/16] gic-v2: Write HCR only on change
Date: Wed, 28 Nov 2018 23:32:07 +0200	[thread overview]
Message-ID: <1543440731-21947-13-git-send-email-andrii.anisov@gmail.com> (raw)
In-Reply-To: <1543440731-21947-1-git-send-email-andrii.anisov@gmail.com>

From: Andrii Anisov <andrii_anisov@epam.com>

This saves one write to peripheral HCR register per hypervisor entry for
most cases.

Signed-off-by: Andrii Anisov <andrii_anisov@epam.com>
---
 xen/arch/arm/gic-v2.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
index 1a744c5..25147bd 100644
--- a/xen/arch/arm/gic-v2.c
+++ b/xen/arch/arm/gic-v2.c
@@ -579,14 +579,17 @@ static void gicv2_write_lr(int lr, const struct gic_lr *lr_reg)
 
 static void gicv2_hcr_status(uint32_t flag, bool status)
 {
-    uint32_t hcr = readl_gich(GICH_HCR);
+    uint32_t hcr, ohcr;
+
+    ohcr = hcr = readl_gich(GICH_HCR);
 
     if ( status )
         hcr |= flag;
     else
         hcr &= (~flag);
 
-    writel_gich(hcr, GICH_HCR);
+    if ( hcr != ohcr )
+        writel_gich(hcr, GICH_HCR);
 }
 
 static unsigned int gicv2_read_vmcr_priority(void)
-- 
2.7.4


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  parent reply	other threads:[~2018-11-28 21:32 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1543440731-21947-1-git-send-email-andrii.anisov@gmail.com>
2018-11-28 21:31 ` [RFC 01/16] xen/arm: Re-enable interrupt later in the trap path Andrii Anisov
2018-11-28 22:00   ` Julien Grall
2019-07-30 17:34     ` [Xen-devel] " Andrii Anisov
2019-07-30 20:46       ` Julien Grall
2018-11-28 21:31 ` [RFC 02/16] hack: drop GIC v3 support Andrii Anisov
2018-11-29 12:08   ` Andre Przywara
2018-11-28 21:31 ` [RFC 03/16] vgic: move pause_flags check out of vgic spinlock Andrii Anisov
2018-11-28 22:02   ` Julien Grall
2018-11-28 21:31 ` [RFC 04/16] vgic: move irq_to_pending out of lock Andrii Anisov
2018-11-29 11:07   ` Julien Grall
2018-11-28 21:32 ` [RFC 05/16] gic-vgic: Drop an excessive clear_lrs Andrii Anisov
2018-12-11 14:33   ` Julien Grall
2018-12-12 11:01     ` Andrii Anisov
2018-12-12 11:55       ` Julien Grall
2018-11-28 21:32 ` [RFC 06/16] gic: drop interrupts enabling on interrupts processing Andrii Anisov
2018-11-28 22:06   ` Julien Grall
2018-12-12 12:10     ` Julien Grall
2018-11-28 21:32 ` [RFC 07/16] gic-vgic:vgic: do not keep disabled IRQs in any of queues Andrii Anisov
2018-11-28 21:32 ` [RFC 08/16] gic: separate ppi processing Andrii Anisov
2018-12-12 12:37   ` Andrii Anisov
2018-12-12 12:46     ` Julien Grall
2018-12-12 12:52       ` Andrii Anisov
2018-12-12 13:46         ` Julien Grall
2018-11-28 21:32 ` [RFC 09/16] gic-vgic:vgic: avoid excessive conversions Andrii Anisov
2018-11-29 10:23   ` Julien Grall
2018-11-28 21:32 ` [RFC 10/16] gic:vgic:gic-vgic: introduce non-atomic bitops Andrii Anisov
2018-11-29 12:14   ` Andre Przywara
2018-11-29 16:07     ` Julien Grall
2018-12-03 12:33     ` Andrii Anisov
2018-12-03 12:58       ` Julien Grall
2018-12-03 13:05         ` Andrii Anisov
2018-12-03 13:08           ` Julien Grall
2018-12-03 16:37       ` Andre Przywara
2018-11-28 21:32 ` [RFC 11/16] irq: skip action avalability check for guest's IRQ Andrii Anisov
2018-12-11 14:48   ` Julien Grall
2018-12-12 11:30     ` Andrii Anisov
2018-12-12 11:59       ` Julien Grall
2018-12-12 13:51         ` Andrii Anisov
2018-12-12 14:49           ` Julien Grall
2018-12-12 14:58             ` Andrii Anisov
2018-12-12 15:08               ` Julien Grall
2018-12-12 15:57                 ` Andrii Anisov
2018-11-28 21:32 ` Andrii Anisov [this message]
2018-11-29 16:36   ` [RFC 12/16] gic-v2: Write HCR only on change Julien Grall
2018-11-28 21:32 ` [RFC 13/16] gic-vgic: skip irqs locking Andrii Anisov
2018-12-12 12:07   ` Julien Grall
2018-12-12 12:35     ` Andrii Anisov
2018-12-12 12:44       ` Julien Grall
2018-12-12 12:47         ` Andrii Anisov
2018-11-28 21:32 ` [RFC 14/16] hack: arm/domain: simplify context restore from idle vcpu Andrii Anisov
2018-11-29 15:53   ` Julien Grall
2018-11-29 16:00   ` Wei Liu
2018-11-28 21:32 ` [RFC 15/16] hack: move gicv2 LRs reads and writes out of spinlocks Andrii Anisov
2018-11-28 21:58   ` Julien Grall
2018-11-28 21:32 ` [RFC 16/16] gic: vgic: align frequently accessed data by cache line size Andrii Anisov
2018-11-29 16:24   ` Julien Grall
2018-11-29  7:40 ` [RFC 00/16] Old GIC (gic-vgic) optimizations for GICV2 Andrii Anisov
2018-11-29 11:00   ` Julien Grall
2018-11-29 12:07   ` Andre Przywara

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