From: Andrew Jones <drjones@redhat.com>
To: Oliver Upton <oupton@google.com>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
Marc Zyngier <maz@kernel.org>,
Raghavendra Rao Anata <rananta@google.com>,
Peter Shier <pshier@google.com>,
Sean Christopherson <seanjc@google.com>,
David Matlack <dmatlack@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
linux-arm-kernel@lists.infradead.org,
Jim Mattson <jmattson@google.com>
Subject: Re: [PATCH v3 08/12] KVM: arm64: Allow userspace to configure a vCPU's virtual offset
Date: Wed, 21 Jul 2021 18:16:31 +0200 [thread overview]
Message-ID: <20210721161631.mrfiuusc5zou4we5@gator> (raw)
In-Reply-To: <20210719184949.1385910-9-oupton@google.com>
On Mon, Jul 19, 2021 at 06:49:45PM +0000, Oliver Upton wrote:
> Add a new vCPU attribute that allows userspace to directly manipulate
> the virtual counter-timer offset. Exposing such an interface allows for
> the precise migration of guest virtual counter-timers, as it is an
> indepotent interface.
>
> Uphold the existing behavior of writes to CNTVOFF_EL2 for this new
> interface, wherein a write to a single vCPU is broadcasted to all vCPUs
> within a VM.
>
> Signed-off-by: Oliver Upton <oupton@google.com>
> ---
> Documentation/virt/kvm/devices/vcpu.rst | 22 ++++++++
> arch/arm64/include/uapi/asm/kvm.h | 1 +
> arch/arm64/kvm/arch_timer.c | 68 ++++++++++++++++++++++++-
> 3 files changed, 89 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
> index b46d5f742e69..7b57cba3416a 100644
> --- a/Documentation/virt/kvm/devices/vcpu.rst
> +++ b/Documentation/virt/kvm/devices/vcpu.rst
> @@ -139,6 +139,28 @@ configured values on other VCPUs. Userspace should configure the interrupt
> numbers on at least one VCPU after creating all VCPUs and before running any
> VCPUs.
>
> +2.2. ATTRIBUTE: KVM_ARM_VCPU_TIMER_OFFSET_VTIMER
> +------------------------------------------------
> +
> +:Parameters: Pointer to a 64-bit unsigned counter-timer offset.
> +
> +Returns:
> +
> + ======= ======================================
> + -EFAULT Error reading/writing the provided
> + parameter address
> + -ENXIO Attribute not supported
> + ======= ======================================
> +
> +Specifies the guest's virtual counter-timer offset from the host's
> +virtual counter. The guest's virtual counter is then derived by
> +the following equation:
> +
> + guest_cntvct = host_cntvct - KVM_ARM_VCPU_TIMER_OFFSET_VTIMER
> +
> +KVM does not allow the use of varying offset values for different vCPUs;
> +the last written offset value will be broadcasted to all vCPUs in a VM.
> +
> 3. GROUP: KVM_ARM_VCPU_PVTIME_CTRL
> ==================================
>
> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
> index b3edde68bc3e..008d0518d2b1 100644
> --- a/arch/arm64/include/uapi/asm/kvm.h
> +++ b/arch/arm64/include/uapi/asm/kvm.h
> @@ -365,6 +365,7 @@ struct kvm_arm_copy_mte_tags {
> #define KVM_ARM_VCPU_TIMER_CTRL 1
> #define KVM_ARM_VCPU_TIMER_IRQ_VTIMER 0
> #define KVM_ARM_VCPU_TIMER_IRQ_PTIMER 1
> +#define KVM_ARM_VCPU_TIMER_OFFSET_VTIMER 2
> #define KVM_ARM_VCPU_PVTIME_CTRL 2
> #define KVM_ARM_VCPU_PVTIME_IPA 0
>
> diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
> index 3df67c127489..d2b1b13af658 100644
> --- a/arch/arm64/kvm/arch_timer.c
> +++ b/arch/arm64/kvm/arch_timer.c
> @@ -1305,7 +1305,7 @@ static void set_timer_irqs(struct kvm *kvm, int vtimer_irq, int ptimer_irq)
> }
> }
>
> -int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +int kvm_arm_timer_set_attr_irq(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> {
> int __user *uaddr = (int __user *)(long)attr->addr;
> struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
> @@ -1338,7 +1338,39 @@ int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> return 0;
> }
>
> -int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +int kvm_arm_timer_set_attr_offset(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +{
> + u64 __user *uaddr = (u64 __user *)(long)attr->addr;
> + u64 offset;
> +
> + if (get_user(offset, uaddr))
> + return -EFAULT;
> +
> + switch (attr->attr) {
> + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER:
> + update_vtimer_cntvoff(vcpu, offset);
> + break;
> + default:
> + return -ENXIO;
> + }
> +
> + return 0;
> +}
> +
> +int kvm_arm_timer_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +{
> + switch (attr->attr) {
> + case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
> + case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
> + return kvm_arm_timer_set_attr_irq(vcpu, attr);
> + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER:
> + return kvm_arm_timer_set_attr_offset(vcpu, attr);
> + }
> +
> + return -ENXIO;
> +}
> +
> +int kvm_arm_timer_get_attr_irq(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> {
> int __user *uaddr = (int __user *)(long)attr->addr;
> struct arch_timer_context *timer;
> @@ -1359,11 +1391,43 @@ int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> return put_user(irq, uaddr);
> }
>
> +int kvm_arm_timer_get_attr_offset(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +{
> + u64 __user *uaddr = (u64 __user *)(long)attr->addr;
> + struct arch_timer_context *timer;
> + u64 offset;
> +
> + switch (attr->attr) {
> + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER:
> + timer = vcpu_vtimer(vcpu);
> + break;
> + default:
> + return -ENXIO;
> + }
> +
> + offset = timer_get_offset(timer);
> + return put_user(offset, uaddr);
> +}
> +
> +int kvm_arm_timer_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> +{
> + switch (attr->attr) {
> + case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
> + case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
> + return kvm_arm_timer_get_attr_irq(vcpu, attr);
> + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER:
> + return kvm_arm_timer_get_attr_offset(vcpu, attr);
> + }
> +
> + return -ENXIO;
> +}
> +
> int kvm_arm_timer_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
> {
> switch (attr->attr) {
> case KVM_ARM_VCPU_TIMER_IRQ_VTIMER:
> case KVM_ARM_VCPU_TIMER_IRQ_PTIMER:
> + case KVM_ARM_VCPU_TIMER_OFFSET_VTIMER:
> return 0;
> }
>
> --
> 2.32.0.402.g57bb445576-goog
>
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
>
Reviewed-by: Andrew Jones <drjones@redhat.com>
next prev parent reply other threads:[~2021-07-21 16:16 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 18:49 [PATCH v3 00/12] KVM: Add idempotent controls for migrating system counter state Oliver Upton
2021-07-19 18:49 ` [PATCH v3 01/12] KVM: x86: Report host tsc and realtime values in KVM_GET_CLOCK Oliver Upton
2021-07-19 18:49 ` [PATCH v3 02/12] KVM: x86: Refactor tsc synchronization code Oliver Upton
2021-07-19 18:49 ` [PATCH v3 03/12] KVM: x86: Expose TSC offset controls to userspace Oliver Upton
2021-07-19 18:49 ` [PATCH v3 04/12] tools: arch: x86: pull in pvclock headers Oliver Upton
2021-07-19 18:49 ` [PATCH v3 05/12] selftests: KVM: Add test for KVM_{GET,SET}_CLOCK Oliver Upton
2021-07-19 18:49 ` [PATCH v3 06/12] selftests: KVM: Add helpers for vCPU device attributes Oliver Upton
2021-07-19 18:49 ` [PATCH v3 07/12] selftests: KVM: Introduce system counter offset test Oliver Upton
2021-07-19 18:49 ` [PATCH v3 08/12] KVM: arm64: Allow userspace to configure a vCPU's virtual offset Oliver Upton
2021-07-21 16:16 ` Andrew Jones [this message]
2021-07-19 18:49 ` [PATCH v3 09/12] selftests: KVM: Add support for aarch64 to system_counter_offset_test Oliver Upton
2021-07-21 16:26 ` Andrew Jones
2021-07-19 18:49 ` [PATCH v3 10/12] KVM: arm64: Provide userspace access to the physical counter offset Oliver Upton
2021-07-21 16:44 ` Andrew Jones
2021-07-19 18:49 ` [PATCH v3 11/12] selftests: KVM: Test physical counter offsetting Oliver Upton
2021-07-21 16:46 ` Andrew Jones
2021-07-19 18:49 ` [PATCH v3 12/12] selftests: KVM: Add counter emulation benchmark Oliver Upton
2021-07-21 18:59 ` Andrew Jones
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210721161631.mrfiuusc5zou4we5@gator \
--to=drjones@redhat.com \
--cc=dmatlack@google.com \
--cc=jmattson@google.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=maz@kernel.org \
--cc=oupton@google.com \
--cc=pbonzini@redhat.com \
--cc=pshier@google.com \
--cc=rananta@google.com \
--cc=seanjc@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).