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From: Dave Martin <Dave.Martin@arm.com>
To: kvmarm@lists.cs.columbia.edu
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
	"Okamoto Takayuki" <tokamoto@jp.fujitsu.com>,
	"Christoffer Dall" <cdall@kernel.org>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Marc Zyngier" <marc.zyngier@arm.com>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Will Deacon" <will.deacon@arm.com>,
	"Julien Grall" <Julien.Grall@arm.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 07/25] arm64/sve: Clarify role of the VQ map maintenance functions
Date: Thu, 17 Jan 2019 20:33:21 +0000	[thread overview]
Message-ID: <1547757219-19439-8-git-send-email-Dave.Martin@arm.com> (raw)
In-Reply-To: <1547757219-19439-1-git-send-email-Dave.Martin@arm.com>

The roles of sve_init_vq_map(), sve_update_vq_map() and
sve_verify_vq_map() are highly non-obvious to anyone who has not dug
through cpufeatures.c in detail.

Since the way these functions interact with each other is more
important here than a full understanding of the cpufeatures code, this
patch adds comments to make the functions' roles clearer.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
---
 arch/arm64/kernel/fpsimd.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 64729e2..92c2331 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -647,6 +647,10 @@ static void sve_probe_vqs(DECLARE_BITMAP(map, SVE_VQ_MAX))
 	}
 }
 
+/*
+ * Initialise the set of known supported VQs for the boot CPU.
+ * This is called during kernel boot, before secondary CPUs are brought up.
+ */
 void __init sve_init_vq_map(void)
 {
 	sve_probe_vqs(sve_vq_map);
@@ -656,6 +660,7 @@ void __init sve_init_vq_map(void)
 /*
  * If we haven't committed to the set of supported VQs yet, filter out
  * those not supported by the current CPU.
+ * This function is called during the bring-up of early secondary CPUs only.
  */
 void sve_update_vq_map(void)
 {
@@ -666,7 +671,10 @@ void sve_update_vq_map(void)
 	bitmap_or(sve_vq_partial_map, sve_vq_partial_map, tmp_map, SVE_VQ_MAX);
 }
 
-/* Check whether the current CPU supports all VQs in the committed set */
+/*
+ * Check whether the current CPU supports all VQs in the committed set.
+ * This function is called during the bring-up of late secondary CPUs only.
+ */
 int sve_verify_vq_map(void)
 {
 	DECLARE_BITMAP(tmp_map, SVE_VQ_MAX);
-- 
2.1.4


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  parent reply	other threads:[~2019-01-17 20:37 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-17 20:33 [PATCH v4 00/25] KVM: arm64: SVE guest support Dave Martin
2019-01-17 20:33 ` [PATCH v4 01/25] KVM: Documentation: Document arm64 core registers in detail Dave Martin
2019-01-17 20:33 ` [PATCH v4 02/25] arm64: fpsimd: Always set TIF_FOREIGN_FPSTATE on task state flush Dave Martin
2019-01-17 20:33 ` [PATCH v4 03/25] KVM: arm64: Delete orphaned declaration for __fpsimd_enabled() Dave Martin
2019-01-17 20:33 ` [PATCH v4 04/25] KVM: arm64: Refactor kvm_arm_num_regs() for easier maintenance Dave Martin
2019-01-17 20:33 ` [PATCH v4 05/25] KVM: arm64: Add missing #include of <linux/bitmap.h> to kvm_host.h Dave Martin
2019-01-17 20:33 ` [PATCH v4 06/25] arm64/sve: Check SVE virtualisability Dave Martin
2019-01-17 20:33 ` Dave Martin [this message]
2019-01-17 20:33 ` [PATCH v4 08/25] arm64/sve: Enable SVE state tracking for non-task contexts Dave Martin
2019-01-17 20:33 ` [PATCH v4 09/25] KVM: arm64: Add a vcpu flag to control SVE visibility for the guest Dave Martin
2019-01-17 20:33 ` [PATCH v4 10/25] KVM: arm64: Propagate vcpu into read_id_reg() Dave Martin
2019-01-17 20:33 ` [PATCH v4 11/25] KVM: arm64: Extend reset_unknown() to handle mixed RES0/UNKNOWN registers Dave Martin
2019-01-17 20:33 ` [PATCH v4 12/25] KVM: arm64: Support runtime sysreg filtering for KVM_GET_REG_LIST Dave Martin
2019-01-17 20:33 ` [PATCH v4 13/25] KVM: arm64/sve: System register context switch and access support Dave Martin
2019-01-18 16:42   ` Marc Zyngier
2019-01-22 16:27     ` Dave Martin
2019-01-17 20:33 ` [PATCH v4 14/25] KVM: arm64/sve: Context switch the SVE registers Dave Martin
2019-01-18 17:15   ` Marc Zyngier
2019-01-22 17:12     ` Dave Martin
2019-01-17 20:33 ` [PATCH v4 15/25] KVM: Allow 2048-bit register access via ioctl interface Dave Martin
2019-01-17 20:33 ` [PATCH v4 16/25] KVM: arm64: Reject ioctl access to FPSIMD V-regs on SVE vcpus Dave Martin
2019-01-17 20:33 ` [PATCH v4 17/25] KVM: arm64/sve: Add SVE support to register access ioctl interface Dave Martin
2019-01-18 17:58   ` Marc Zyngier
2019-01-22 17:24     ` Dave Martin
2019-01-17 20:33 ` [PATCH v4 18/25] KVM: arm64: Enumerate SVE register indices for KVM_GET_REG_LIST Dave Martin
2019-01-17 20:33 ` [PATCH v4 19/25] arm64/sve: In-kernel vector length availability query interface Dave Martin
2019-01-17 20:33 ` [PATCH v4 20/25] KVM: arm/arm64: Add hook to finalize the vcpu configuration Dave Martin
2019-01-17 20:33 ` [PATCH v4 21/25] KVM: arm64/sve: Add pseudo-register for the guest's vector lengths Dave Martin
2019-01-17 20:33 ` [PATCH v4 22/25] KVM: arm64/sve: Allow userspace to enable SVE for vcpus Dave Martin
2019-01-17 20:33 ` [PATCH v4 23/25] KVM: arm64: Add a capabillity to advertise SVE support Dave Martin
2019-01-17 20:33 ` [PATCH v4 24/25] KVM: Document errors for KVM_GET_ONE_REG and KVM_SET_ONE_REG Dave Martin
2019-01-17 20:33 ` [PATCH v4 25/25] KVM: arm64/sve: Document KVM API extensions for SVE Dave Martin

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