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 10/14] KVM: arm64/sve: Explain validity checks in set_sve_vls()
Date: Thu, 18 Apr 2019 17:07:07 +0100 [thread overview]
Message-ID: <1555603631-8107-11-git-send-email-Dave.Martin@arm.com> (raw)
In-Reply-To: <1555603631-8107-1-git-send-email-Dave.Martin@arm.com>
Correct virtualization of SVE relies for correctness on code in
set_sve_vls() that verifies consistency between the set of vector
lengths requested by userspace and the set of vector lengths
available on the host.
However, the purpose of this code is not obvious, and not likely to
be apparent at all to people who do not have detailed knowledge of
the SVE system-level architecture.
This patch adds a suitable comment to explain what these checks are
for.
No functional change.
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/guest.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 5bb909c..3ae2f82 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -264,6 +264,13 @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
if (max_vq > sve_vq_from_vl(kvm_sve_max_vl))
return -EINVAL;
+ /*
+ * Vector lengths supported by the host can't currently be
+ * hidden from the guest individually: instead we can only set a
+ * maxmium via ZCR_EL2.LEN. So, make sure the available vector
+ * lengths match the set requested exactly up to the requested
+ * maximum:
+ */
for (vq = SVE_VQ_MIN; vq <= max_vq; ++vq)
if (vq_present(&vqs, vq) != sve_vq_available(vq))
return -EINVAL;
--
2.1.4
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next prev parent reply other threads:[~2019-04-18 16:09 UTC|newest]
Thread overview: 23+ 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 ` [PATCH v2 01/14] arm64/sve: Clarify vq map semantics 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 16:07 ` [PATCH v2 03/14] KVM: arm: Make vcpu finalization stubs into inline functions Dave Martin
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 ` [PATCH v2 05/14] KVM: arm64/sve: Clean up UAPI register ID definitions 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 ` [PATCH v2 07/14] KVM: arm64/sve: Make register ioctl access errors more consistent Dave Martin
2019-04-25 12:30 ` Alex Bennée
2019-04-25 13:04 ` Dave Martin
2019-04-25 15:04 ` Alex Bennée
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 ` [PATCH v2 09/14] KVM: arm64/sve: Simplify KVM_REG_ARM64_SVE_VLS array sizing Dave Martin
2019-04-18 16:07 ` Dave Martin [this message]
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 ` [PATCH v2 12/14] KVM: Clarify capability requirements for KVM_ARM_VCPU_FINALIZE 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 ` [PATCH v2 14/14] KVM: arm64: Clarify access behaviour for out-of-range SVE register slice IDs Dave Martin
2019-04-24 9:21 ` [PATCH v2 00/14] KVM: arm64: SVE cleanups Alex Bennée
2019-04-24 9:38 ` Marc Zyngier
2019-04-25 12:35 ` Alex Bennée
2019-04-25 13:05 ` Dave Martin
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