kernel/linux.git/virt/kvm/arm/arch_timer.c, branch v5.0.3

KVM: arm/arm64: arch_timer: Simplify kvm_timer_vcpu_terminate

2018-12-19T17:47:07+00:00

kvm_timer_vcpu_terminate can only be called in two scenarios: 1. As part of cleanup during a failed VCPU create 2. As part of freeing the whole VM (struct kvm refcount == 0) In the first case, we cannot have programmed any timers or mapped any IRQs, and therefore we do not have to cancel anything or unmap anything. In the second case, the VCPU will have gone through kvm_timer_vcpu_put, which will have canceled the emulated physical timer's hrtimer, and we do not need to that here as well. We also do not care if the irq is recorded as mapped or not in the VGIC data structure, because the whole VM is going away. That leaves us only with having to ensure that we cancel the bg_timer if we were blocking the last time we called kvm_timer_vcpu_put(). Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier

KVM: arm/arm64: Remove arch timer workqueue

2018-12-19T17:47:07+00:00

The use of a work queue in the hrtimer expire function for the bg_timer is a leftover from the time when we would inject interrupts when the bg_timer expired. Since we are no longer doing that, we can instead call kvm_vcpu_wake_up() directly from the hrtimer function and remove all workqueue functionality from the arch timer code. Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier

KVM: arm/arm64: Fix lost IRQs from emulated physcial timer when blocked

2018-07-31T06:53:20+00:00

When the VCPU is blocked (for example from WFI) we don't inject the physical timer interrupt if it should fire while the CPU is blocked, but instead we just wake up the VCPU and expect kvm_timer_vcpu_load to take care of injecting the interrupt. Unfortunately, kvm_timer_vcpu_load() doesn't actually do that, it only has support to schedule a soft timer if the emulated phys timer is expected to fire in the future. Follow the same pattern as kvm_timer_update_state() and update the irq state after potentially scheduling a soft timer. Reported-by: Andre Przywara Cc: Stable # 4.15+ Fixes: bbdd52cfcba29 ("KVM: arm/arm64: Avoid phys timer emulation in vcpu entry/exit") Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier

KVM: arm/arm64: Fix potential loss of ptimer interrupts

2018-07-31T06:53:16+00:00

kvm_timer_update_state() is called when changing the phys timer configuration registers, either via vcpu reset, as a result of a trap from the guest, or when userspace programs the registers. phys_timer_emulate() is in turn called by kvm_timer_update_state() to either cancel an existing software timer, or program a new software timer, to emulate the behavior of a real phys timer, based on the change in configuration registers. Unfortunately, the interaction between these two functions left a small race; if the conceptual emulated phys timer should actually fire, but the soft timer hasn't executed its callback yet, we cancel the timer in phys_timer_emulate without injecting an irq. This only happens if the check in kvm_timer_update_state is called before the timer should fire, which is relatively unlikely, but possible. The solution is to update the state of the phys timer after calling phys_timer_emulate, which will pick up the pending timer state and update the interrupt value. Note that this leaves the opportunity of raising the interrupt twice, once in the just-programmed soft timer, and once in kvm_timer_update_state. Since this always happens synchronously with the VCPU execution, there is no harm in this, and the guest ever only sees a single timer interrupt. Cc: Stable # 4.15+ Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier

Merge tag 'kvm-arm-fixes-for-v4.16-2' into HEAD

2018-03-19T17:43:01+00:00

Resolve conflicts with current mainline

KVM: arm/arm64: Move vcpu_load call after kvm_vcpu_first_run_init

2018-03-19T10:53:09+00:00

Moving the call to vcpu_load() in kvm_arch_vcpu_ioctl_run() to after we've called kvm_vcpu_first_run_init() simplifies some of the vgic and there is also no need to do vcpu_load() for things such as handling the immediate_exit flag. Reviewed-by: Julien Grall Reviewed-by: Marc Zyngier Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier

KVM: arm/arm64: Reduce verbosity of KVM init log

2018-03-14T18:29:14+00:00

On my GICv3 system, the following is printed to the kernel log at boot: kvm [1]: 8-bit VMID kvm [1]: IDMAP page: d20e35000 kvm [1]: HYP VA range: 800000000000:ffffffffffff kvm [1]: vgic-v2@2c020000 kvm [1]: GIC system register CPU interface enabled kvm [1]: vgic interrupt IRQ1 kvm [1]: virtual timer IRQ4 kvm [1]: Hyp mode initialized successfully The KVM IDMAP is a mapping of a statically allocated kernel structure, and so printing its physical address leaks the physical placement of the kernel when physical KASLR in effect. So change the kvm_info() to kvm_debug() to remove it from the log output. While at it, trim the output a bit more: IRQ numbers can be found in /proc/interrupts, and the HYP VA and vgic-v2 lines are not highly informational either. Cc: Acked-by: Will Deacon Acked-by: Christoffer Dall Signed-off-by: Ard Biesheuvel Signed-off-by: Marc Zyngier

KVM: arm/arm64: Reset mapped IRQs on VM reset

2018-03-14T18:29:14+00:00

We currently don't allow resetting mapped IRQs from userspace, because their state is controlled by the hardware. But we do need to reset the state when the VM is reset, so we provide a function for the 'owner' of the mapped interrupt to reset the interrupt state. Currently only the timer uses mapped interrupts, so we call this function from the timer reset logic. Cc: stable@vger.kernel.org Fixes: 4c60e360d6df ("KVM: arm/arm64: Provide a get_input_level for the arch timer") Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier

KVM: arm/arm64: No need to zero CNTVOFF in kvm_timer_vcpu_put() for VHE

2018-02-26T09:48:02+00:00

In AArch64/AArch32, the virtual counter uses a fixed virtual offset of zero in the following situations as per ARMv8 specifications: 1) HCR_EL2.E2H is 1, and CNTVCT_EL0/CNTVCT are read from EL2. 2) HCR_EL2.{E2H, TGE} is {1, 1}, and either: — CNTVCT_EL0 is read from Non-secure EL0 or EL2. — CNTVCT is read from Non-secure EL0. So, no need to zero CNTVOFF_EL2/CNTVOFF for VHE case. Acked-by: Marc Zyngier Acked-by: Christoffer Dall Signed-off-by: Shanker Donthineni Signed-off-by: Christoffer Dall

KVM: arm/arm64: Fix arch timers with userspace irqchips

2018-02-15T19:58:29+00:00

When introducing support for irqchip in userspace we needed a way to mask the timer signal to prevent the guest continuously exiting due to a screaming timer. We did this by disabling the corresponding percpu interrupt on the host interrupt controller, because we cannot rely on the host system having a GIC, and therefore cannot make any assumptions about having an active state to hide the timer signal. Unfortunately, when introducing this feature, it became entirely possible that a VCPU which belongs to a VM that has a userspace irqchip can disable the vtimer irq on the host on some physical CPU, and then go away without ever enabling the vtimer irq on that physical CPU again. This means that using irqchips in userspace on a system that also supports running VMs with an in-kernel GIC can prevent forward progress from in-kernel GIC VMs. Later on, when we started taking virtual timer interrupts in the arch timer code, we would also leave this timer state active for userspace irqchip VMs, because we leave it up to a VGIC-enabled guest to deactivate the hardware IRQ using the HW bit in the LR. Both issues are solved by only using the enable/disable trick on systems that do not have a host GIC which supports the active state, because all VMs on such systems must use irqchips in userspace. Systems that have a working GIC with support for an active state use the active state to mask the timer signal for both userspace and in-kernel irqchips. Cc: Alexander Graf Reviewed-by: Marc Zyngier Cc: # v4.12+ Fixes: d9e139778376 ("KVM: arm/arm64: Support arch timers with a userspace gic") Signed-off-by: Christoffer Dall