[PATCH v2 04/14] KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs

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From: Dave Martin <Dave.Martin@arm.com>
To: kvmarm@lists.cs.columbia.edu
Cc: 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>,
	Zhang Lei <zhang.lei@jp.fujitsu.com>,
	Julien Grall <julien.grall@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 04/14] KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs
Date: Thu, 18 Apr 2019 17:07:01 +0100	[thread overview]
Message-ID: <1555603631-8107-5-git-send-email-Dave.Martin@arm.com> (raw)
In-Reply-To: <1555603631-8107-1-git-send-email-Dave.Martin@arm.com>

Because of the logic in kvm_arm_sys_reg_{get,set}_reg() and
sve_id_visibility(), we should never call
{get,set}_id_aa64zfr0_el1() for a vcpu where !vcpu_has_sve(vcpu).

To avoid the code giving the impression that it is valid for these
functions to be called in this situation, and to help the compiler
make the right optimisation decisions, this patch adds WARN_ON()
for these cases.

Given the way the logic is spread out, this seems preferable to
dropping the checks altogether.

Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
 arch/arm64/kvm/sys_regs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 09e9b06..7046c76 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1144,7 +1144,7 @@ static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 {
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	val = guest_id_aa64zfr0_el1(vcpu);
@@ -1159,7 +1159,7 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 	int err;
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	err = reg_from_user(&val, uaddr, id);
-- 
2.1.4

WARNING: multiple messages have this Message-ID (diff)

From: Dave Martin <Dave.Martin@arm.com>
To: kvmarm@lists.cs.columbia.edu
Cc: 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>,
	Zhang Lei <zhang.lei@jp.fujitsu.com>,
	Julien Grall <julien.grall@arm.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 04/14] KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs
Date: Thu, 18 Apr 2019 17:07:01 +0100	[thread overview]
Message-ID: <1555603631-8107-5-git-send-email-Dave.Martin@arm.com> (raw)
Message-ID: <20190418160701.6Ea8hZxBInJpKjE-dh9KFk7wUZbTc5IMsSQMIm9ThdI@z> (raw)
In-Reply-To: <1555603631-8107-1-git-send-email-Dave.Martin@arm.com>

Because of the logic in kvm_arm_sys_reg_{get,set}_reg() and
sve_id_visibility(), we should never call
{get,set}_id_aa64zfr0_el1() for a vcpu where !vcpu_has_sve(vcpu).

To avoid the code giving the impression that it is valid for these
functions to be called in this situation, and to help the compiler
make the right optimisation decisions, this patch adds WARN_ON()
for these cases.

Given the way the logic is spread out, this seems preferable to
dropping the checks altogether.

Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
 arch/arm64/kvm/sys_regs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 09e9b06..7046c76 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1144,7 +1144,7 @@ static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 {
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	val = guest_id_aa64zfr0_el1(vcpu);
@@ -1159,7 +1159,7 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 	int err;
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	err = reg_from_user(&val, uaddr, id);
-- 
2.1.4

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)

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>,
	"Andrew Jones" <drjones@redhat.com>,
	"Zhang Lei" <zhang.lei@jp.fujitsu.com>,
	"Julien Grall" <julien.grall@arm.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 04/14] KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs
Date: Thu, 18 Apr 2019 17:07:01 +0100	[thread overview]
Message-ID: <1555603631-8107-5-git-send-email-Dave.Martin@arm.com> (raw)
In-Reply-To: <1555603631-8107-1-git-send-email-Dave.Martin@arm.com>

Because of the logic in kvm_arm_sys_reg_{get,set}_reg() and
sve_id_visibility(), we should never call
{get,set}_id_aa64zfr0_el1() for a vcpu where !vcpu_has_sve(vcpu).

To avoid the code giving the impression that it is valid for these
functions to be called in this situation, and to help the compiler
make the right optimisation decisions, this patch adds WARN_ON()
for these cases.

Given the way the logic is spread out, this seems preferable to
dropping the checks altogether.

Suggested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
 arch/arm64/kvm/sys_regs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 09e9b06..7046c76 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1144,7 +1144,7 @@ static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 {
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	val = guest_id_aa64zfr0_el1(vcpu);
@@ -1159,7 +1159,7 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
 	int err;
 	u64 val;
 
-	if (!vcpu_has_sve(vcpu))
+	if (WARN_ON(!vcpu_has_sve(vcpu)))
 		return -ENOENT;
 
 	err = reg_from_user(&val, uaddr, id);
-- 
2.1.4


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

next prev parent reply	other threads:[~2019-04-18 16:08 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-18 16:06 [PATCH v2 00/14] KVM: arm64: SVE cleanups Dave Martin
2019-04-18 16:06 ` Dave Martin
2019-04-18 16:06 ` Dave Martin
2019-04-18 16:06 ` [PATCH v2 01/14] arm64/sve: Clarify vq map semantics Dave Martin
2019-04-18 16:06   ` Dave Martin
2019-04-18 16:06   ` Dave Martin
2019-04-18 16:06 ` [PATCH v2 02/14] KVM: arm/arm64: Demote kvm_arm_init_arch_resources() to just set up SVE Dave Martin
2019-04-18 16:06   ` Dave Martin
2019-04-18 16:06   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 03/14] KVM: arm: Make vcpu finalization stubs into inline functions Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` Dave Martin [this message]
2019-04-18 16:07   ` [PATCH v2 04/14] KVM: arm64/sve: sys_regs: Demote redundant vcpu_has_sve() checks to WARNs Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 05/14] KVM: arm64/sve: Clean up UAPI register ID definitions Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 06/14] KVM: arm64/sve: Miscellaneous tidyups in guest.c Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 07/14] KVM: arm64/sve: Make register ioctl access errors more consistent Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-25 12:30   ` Alex Bennée
2019-04-25 12:30     ` Alex Bennée
2019-04-25 13:04     ` Dave Martin
2019-04-25 13:04       ` Dave Martin
2019-04-25 13:04       ` Dave Martin
2019-04-25 15:04       ` Alex Bennée
2019-04-25 15:04         ` Alex Bennée
2019-04-25 15:27         ` Dave Martin
2019-04-25 15:27           ` Dave Martin
2019-04-25 15:27           ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 08/14] KVM: arm64/sve: WARN when avoiding divide-by-zero in sve_reg_to_region() Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 09/14] KVM: arm64/sve: Simplify KVM_REG_ARM64_SVE_VLS array sizing Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 10/14] KVM: arm64/sve: Explain validity checks in set_sve_vls() Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 11/14] KVM: arm/arm64: Clean up vcpu finalization function parameter naming Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 12/14] KVM: Clarify capability requirements for KVM_ARM_VCPU_FINALIZE Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 13/14] KVM: Clarify KVM_{SET, GET}_ONE_REG error code documentation Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07 ` [PATCH v2 14/14] KVM: arm64: Clarify access behaviour for out-of-range SVE register slice IDs Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-18 16:07   ` Dave Martin
2019-04-24  9:21 ` [PATCH v2 00/14] KVM: arm64: SVE cleanups Alex Bennée
2019-04-24  9:21   ` Alex Bennée
2019-04-24  9:38   ` Marc Zyngier
2019-04-24  9:38     ` Marc Zyngier
2019-04-25 12:35 ` Alex Bennée
2019-04-25 12:35   ` Alex Bennée
2019-04-25 13:05   ` Dave Martin
2019-04-25 13:05     ` Dave Martin
2019-04-25 13:05     ` Dave Martin

find likely ancestor, descendant, or conflicting patches for this message:
dfblob:09e9b06 dfblob:09e9b06 dfblob:09e9b06 dfblob:7046c76
dfblob:7046c76 dfblob:7046c76
	(help)

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