kernel/linux.git/arch/arm64/kvm/arch_timer.c, branch v6.4

Merge branch kvm-arm64/timer-vm-offsets into kvmarm-master/next

2023-04-21T08:36:40+00:00

* kvm-arm64/timer-vm-offsets: (21 commits) : . : This series aims at satisfying multiple goals: : : - allow a VMM to atomically restore a timer offset for a whole VM : instead of updating the offset each time a vcpu get its counter : written : : - allow a VMM to save/restore the physical timer context, something : that we cannot do at the moment due to the lack of offsetting : : - provide a framework that is suitable for NV support, where we get : both global and per timer, per vcpu offsetting, and manage : interrupts in a less braindead way. : : Conflict resolution involves using the new per-vcpu config lock instead : of the home-grown timer lock. : . KVM: arm64: Handle 32bit CNTPCTSS traps KVM: arm64: selftests: Augment existing timer test to handle variable offset KVM: arm64: selftests: Deal with spurious timer interrupts KVM: arm64: selftests: Add physical timer registers to the sysreg list KVM: arm64: nv: timers: Support hyp timer emulation KVM: arm64: nv: timers: Add a per-timer, per-vcpu offset KVM: arm64: Document KVM_ARM_SET_CNT_OFFSETS and co KVM: arm64: timers: Abstract the number of valid timers per vcpu KVM: arm64: timers: Fast-track CNTPCT_EL0 trap handling KVM: arm64: Elide kern_hyp_va() in VHE-specific parts of the hypervisor KVM: arm64: timers: Move the timer IRQs into arch_timer_vm_data KVM: arm64: timers: Abstract per-timer IRQ access KVM: arm64: timers: Rationalise per-vcpu timer init KVM: arm64: timers: Allow save/restoring of the physical timer KVM: arm64: timers: Allow userspace to set the global counter offset KVM: arm64: Expose {un,}lock_all_vcpus() to the rest of KVM KVM: arm64: timers: Allow physical offset without CNTPOFF_EL2 KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer arm64: Add HAS_ECV_CNTPOFF capability arm64: Add CNTPOFF_EL2 register definition ... Signed-off-by: Marc Zyngier

KVM: arm64: nv: timers: Support hyp timer emulation

2023-03-30T18:01:10+00:00

Emulating EL2 also means emulating the EL2 timers. To do so, we expand our timer framework to deal with at most 4 timers. At any given time, two timers are using the HW timers, and the two others are purely emulated. The role of deciding which is which at any given time is left to a mapping function which is called every time we need to make such a decision. Reviewed-by: Colton Lewis Co-developed-by: Christoffer Dall Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-18-maz@kernel.org

KVM: arm64: nv: timers: Add a per-timer, per-vcpu offset

2023-03-30T18:01:10+00:00

Being able to set a global offset isn't enough. With NV, we also need to a per-vcpu, per-timer offset (for example, CNTVCT_EL0 being offset by CNTVOFF_EL2). Use a similar method as the VM-wide offset to have a timer point to the shadow register that contains the offset value. Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-17-maz@kernel.org

KVM: arm64: timers: Abstract the number of valid timers per vcpu

2023-03-30T18:01:10+00:00

We so far have a pretty fixed number of timers to take care of. This is about to change as NV brings another two into the picture, and we must be careful not to try and emulate non-valid timers in a given VM. For this, abstract the number of timers for a given vcpu behind an accessor, which helpfully returns a constant for now. Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-15-maz@kernel.org

KVM: arm64: timers: Move the timer IRQs into arch_timer_vm_data

2023-03-30T18:01:10+00:00

Having the timer IRQs duplicated into each vcpu isn't great, and becomes absolutely awful with NV. So let's move these into the per-VM arch_timer_vm_data structure. This simplifies a lot of code, but requires us to introduce a mutex so that we can reason about userspace trying to change an interrupt number while another vcpu is running, something that wasn't really well handled so far. Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-12-maz@kernel.org

KVM: arm64: timers: Abstract per-timer IRQ access

2023-03-30T18:01:10+00:00

As we are about to move the location of the per-timer IRQ into the VM structure, abstract the location of the IRQ behind an accessor. This will make the repainting sligntly less painful. Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-11-maz@kernel.org

KVM: arm64: timers: Rationalise per-vcpu timer init

2023-03-30T18:01:10+00:00

The way we initialise our timer contexts may be satisfactory for two timers, but will be getting pretty annoying with four. Cleanup the whole thing by removing the code duplication and getting rid of unused IRQ configuration elements. Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-10-maz@kernel.org

KVM: arm64: timers: Allow userspace to set the global counter offset

2023-03-30T18:01:10+00:00

And this is the moment you have all been waiting for: setting the counter offset from userspace. We expose a brand new capability that reports the ability to set the offset for both the virtual and physical sides. In keeping with the architecture, the offset is expressed as a delta that is substracted from the physical counter value. Once this new API is used, there is no going back, and the counters cannot be written to to set the offsets implicitly (the writes are instead ignored). Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-8-maz@kernel.org

KVM: arm64: timers: Allow physical offset without CNTPOFF_EL2

2023-03-30T18:01:09+00:00

CNTPOFF_EL2 is awesome, but it is mostly vapourware, and no publicly available implementation has it. So for the common mortals, let's implement the emulated version of this thing. It means trapping accesses to the physical counter and timer, and emulate some of it as necessary. As for CNTPOFF_EL2, nobody sets the offset yet. Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-6-maz@kernel.org

KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer

2023-03-30T18:01:09+00:00

With ECV and CNTPOFF_EL2, it is very easy to offer an offset for the physical timer. So let's do just that. Nothing can set the offset yet, so this should have no effect whatsoever (famous last words...). Reviewed-by: Colton Lewis Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230330174800.2677007-5-maz@kernel.org