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From: Christoffer Dall <cdall@linaro.org>
To: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org
Cc: Christoffer Dall <cdall@linaro.org>,
	kvm@vger.kernel.org, Marc Zyngier <marc.zyngier@arm.com>,
	Andre Przywara <andre.przywara@arm.com>,
	Vijaya.Kumar@cavium.com
Subject: [PATCH 1/5] KVM: arm/arm64: Clarify GICC_PMR export format
Date: Tue, 21 Mar 2017 12:05:26 +0100	[thread overview]
Message-ID: <20170321110530.15857-2-cdall@linaro.org> (raw)
In-Reply-To: <20170321110530.15857-1-cdall@linaro.org>

We are exporting the format of the priority field as it's stored in the
GICH_VMCR.VMPriMask field using the lower five bits when accessing
register state using the GICC_PMR offset.  This is unfortunate, but it's
ABI already, so we simply have to make it clear.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
 Documentation/virtual/kvm/devices/arm-vgic.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
index 76e61c8..975a904 100644
--- a/Documentation/virtual/kvm/devices/arm-vgic.txt
+++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
@@ -83,6 +83,12 @@ Groups:
 
     Bits for undefined preemption levels are RAZ/WI.
 
+    For historical reasons we export the GICC_PMR register in the format of the
+    GICH_VMCR.VMPriMask field in the lower 5 bits of a word, meaning that
+    userspace must always use the lower 5 bits to communicate with the KVM
+    device and must shift the value left by 3 places to obtain the actual
+    priority mask level.
+
   Limitations:
     - Priorities are not implemented, and registers are RAZ/WI
     - Currently only implemented for KVM_DEV_TYPE_ARM_VGIC_V2.
-- 
2.9.0

WARNING: multiple messages have this Message-ID (diff)
From: cdall@linaro.org (Christoffer Dall)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/5] KVM: arm/arm64: Clarify GICC_PMR export format
Date: Tue, 21 Mar 2017 12:05:26 +0100	[thread overview]
Message-ID: <20170321110530.15857-2-cdall@linaro.org> (raw)
In-Reply-To: <20170321110530.15857-1-cdall@linaro.org>

We are exporting the format of the priority field as it's stored in the
GICH_VMCR.VMPriMask field using the lower five bits when accessing
register state using the GICC_PMR offset.  This is unfortunate, but it's
ABI already, so we simply have to make it clear.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
 Documentation/virtual/kvm/devices/arm-vgic.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
index 76e61c8..975a904 100644
--- a/Documentation/virtual/kvm/devices/arm-vgic.txt
+++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
@@ -83,6 +83,12 @@ Groups:
 
     Bits for undefined preemption levels are RAZ/WI.
 
+    For historical reasons we export the GICC_PMR register in the format of the
+    GICH_VMCR.VMPriMask field in the lower 5 bits of a word, meaning that
+    userspace must always use the lower 5 bits to communicate with the KVM
+    device and must shift the value left by 3 places to obtain the actual
+    priority mask level.
+
   Limitations:
     - Priorities are not implemented, and registers are RAZ/WI
     - Currently only implemented for KVM_DEV_TYPE_ARM_VGIC_V2.
-- 
2.9.0

  reply	other threads:[~2017-03-21 11:05 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-21 11:05 [PATCH 0/5] Clarify GICC_PMR export format and remove struct vmcr Christoffer Dall
2017-03-21 11:05 ` Christoffer Dall
2017-03-21 11:05 ` Christoffer Dall [this message]
2017-03-21 11:05   ` [PATCH 1/5] KVM: arm/arm64: Clarify GICC_PMR export format Christoffer Dall
2017-03-21 11:05 ` [PATCH 2/5] KVM: arm64: vgic: Factor out access_gic_ctlr into separate r/w functions Christoffer Dall
2017-03-21 11:05   ` Christoffer Dall
2017-03-21 11:05 ` [PATCH 3/5] KVM: arm64: vgic: Rename vgic_v3_cpu to vgic_cpu Christoffer Dall
2017-03-21 11:05   ` Christoffer Dall
2017-03-21 11:05 ` [PATCH 4/5] KVM: arm64: vgic: Get rid of struct vmcr for GICv3 Christoffer Dall
2017-03-21 11:05   ` Christoffer Dall
2017-03-21 14:17   ` Marc Zyngier
2017-03-21 14:17     ` Marc Zyngier
2017-03-21 11:05 ` [PATCH 5/5] KVM: arm/arm64: vgic: Get rid of struct vmcr for GICv2 Christoffer Dall
2017-03-21 11:05   ` Christoffer Dall
2017-03-21 14:36   ` Marc Zyngier
2017-03-21 14:36     ` Marc Zyngier
2017-03-21 16:01     ` Christoffer Dall
2017-03-21 16:01       ` Christoffer Dall

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