- 09 Apr, 2017 40 commits
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Alexander Graf authored
If you're running with a userspace gic or other interrupt controller (that is no vgic in the kernel), then you have so far not been able to use the architected timers, because the output of the architected timers, which are driven inside the kernel, was a kernel-only construct between the arch timer code and the vgic. This patch implements the new KVM_CAP_ARM_USER_IRQ feature, where we use a side channel on the kvm_run structure, run->s.regs.device_irq_level, to always notify userspace of the timer output levels when using a userspace irqchip. This works by ensuring that before we enter the guest, if the timer output level has changed compared to what we last told userspace, we don't enter the guest, but instead return to userspace to notify it of the new level. If we are exiting, because of an MMIO for example, and the level changed at the same time, the value is also updated and userspace can sample the line as it needs. This is nicely achieved simply always updating the timer_irq_level field after the main run loop. Note that the kvm_timer_update_irq trace event is changed to show the host IRQ number for the timer instead of the guest IRQ number, because the kernel no longer know which IRQ userspace wires up the timer signal to. Also note that this patch implements all required functionality but does not yet advertise the capability. Reviewed-by:
Alexander Graf <agraf@suse.de> Reviewed-by:
Marc Zyngier <marc.zyngier@arm.com> Signed-off-by:
Christoffer Dall <christoffer.dall@linaro.org>
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Alexander Graf authored
We have 2 modes for dealing with interrupts in the ARM world. We can either handle them all using hardware acceleration through the vgic or we can emulate a gic in user space and only drive CPU IRQ pins from there. Unfortunately, when driving IRQs from user space, we never tell user space about events from devices emulated inside the kernel, which may result in interrupt line state changes, so we lose out on for example timer and PMU events if we run with user space gic emulation. Define an ABI to publish such device output levels to userspace. Reviewed-by:
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Christoffer Dall authored
Currently we check if we have an in-kernel irqchip and if the vgic was properly implemented several places in the arch timer code. But, we already predicate our enablement of the arm timers on having a valid and initialized gic, so we can simply check if the timers are enabled or not. This also gets rid of the ugly "error that's not an error but used to signal that the timer shouldn't poke the gic" construct we have. Reviewed-by:
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Marc Zyngier authored
In order to help people understanding the hyp-stub API that exists between the host kernel and the hypervisor mode (whether a hypervisor has been installed or not), let's document said API. As with any form of documentation, I expect it to become obsolete and completely misleading within 20 minutes after having being merged. Acked-by:
Russell King <rmk+kernel@armlinux.org.uk> Acked-by:
Catalin Marinas <catalin.marinas@arm.com> Signed-off-by:
Christoffer Dall <cdall@linaro.org>
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Marc Zyngier authored
We now return HVC_STUB_ERR when a stub hypercall fails, but we leave whatever was in r0 on success. Zeroing it on return seems like a good idea. Signed-off-by:
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Marc Zyngier authored
We now return HVC_STUB_ERR when a stub hypercall fails, but we leave whatever was in x0 on success. Zeroing it on return seems like a good idea. Signed-off-by:
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Marc Zyngier authored
Nobody is using __hyp_get_vectors anymore, so let's remove both implementations (hyp-stub and KVM). Acked-by:
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Marc Zyngier authored
Nobody is using __hyp_get_vectors anymore, so let's remove both implementations (hyp-stub and KVM). Acked-by:
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Marc Zyngier authored
When the compressed image needs to be relocated to avoid being overwritten by the decompression process, we need to relocate the hyp vectors as well so that we can find them once the decompression has taken effect. For that, we perform the following calculation: u32 v = __hyp_get_vectors(); v += offset; __hyp_set_vectors(v); But we're guaranteed that the initial value of v as returned by __hyp_get_vectors is always __hyp_stub_vectors, because we have just set it by calling __hyp_stub_install. So let's remove the use of __hyp_get_vectors, and directly use __hyp_stub_vectors instead. Acked-by:
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Marc Zyngier authored
Instead of trying to compare the value given by __hyp_get_vectors(), which doesn't offer any real guarantee to be the stub's address, use HVC_RESET_VECTORS to make sure we're in a sane state to reinstall KVM across PM events. Acked-by:
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Marc Zyngier authored
With __cpu_reset_hyp_mode having become fairly dumb, there is no need for kvm_get_idmap_start anymore. Acked-by:
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Marc Zyngier authored
__cpu_reset_hyp_mode doesn't need to be passed any argument now, as the hyp-stub implementations are self-contained, and is now reduced to just calling __hyp_reset_vectors(). Let's drop the wrapper and use the stub hypercall directly. Acked-by:
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Marc Zyngier authored
Should kvm_reboot() be invoked while guest is running, an IPI wil be issued, forcing the guest to exit and HYP being reset to the stubs. We will then try to reenter the guest, only to get an error (HVC_STUB_ERR). This patch allows this case to be gracefully handled by exiting the run loop. Signed-off-by:
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Marc Zyngier authored
Another missing stub hypercall is HVC_SOFT_RESTART. It turns out that it is pretty easy to implement in terms of HVC_RESET_VECTORS (since it needs to turn the MMU off). Tested-by:
Keerthy <j-keerthy@ti.com> Acked-by:
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Marc Zyngier authored
We are now able to use the hyp stub to reset HYP mode. Time to kiss __kvm_hyp_reset goodbye, and use __hyp_reset_vectors. Tested-by:
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Marc Zyngier authored
We now have a full hyp-stub implementation in the KVM init code, but the main KVM code only supports HVC_GET_VECTORS, which is not enough. Instead of reinventing the wheel, let's reuse the init implementation by branching to the idmap page when called with a hyp-stub hypercall. Tested-by:
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Marc Zyngier authored
Now that we have an infrastructure to handle hypercalls in the KVM init code, let's implement HVC_GET_VECTORS there. Tested-by:
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Marc Zyngier authored
In order to restore HYP mode to its original condition, KVM currently implements __kvm_hyp_reset(). As we're moving towards a hyp-stub defined API, it becomes necessary to implement HVC_RESET_VECTORS. This patch adds the HVC_RESET_VECTORS hypercall to the KVM init code, which so far lacked any form of hypercall support. Tested-by:
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Marc Zyngier authored
Let's define a new stub hypercall that resets the HYP configuration to its default: hyp-stub vectors, and MMU disabled. Of course, for the hyp-stub itself, this is a trivial no-op. Hypervisors will have a bit more work to do. Tested-by:
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Marc Zyngier authored
Define a standard return value to be returned when a hyp stub call fails. Signed-off-by:
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Marc Zyngier authored
The KVM code needs to be able to compute the address of symbols in its idmap page (the equivalent of a virt_to_idmap() call). Unfortunately, virt_to_idmap is slightly complicated, depending on the use of arch_phys_to_idmap_offset or not, and none of that is readily available at HYP. Instead, expose a single kimage_voffset variable which contains the offset between a kernel VA and its idmap address, enabling the VA->IDMAP conversion. This allows the KVM code to behave similarily to its arm64 counterpart. Tested-by:
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Marc Zyngier authored
It is not really obvious why the restart address should be in r3 when communicated to the hyp-stub. r1 should be perfectly adequate, and consistent with the rest of the code. Tested-by:
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Marc Zyngier authored
cpu_v7_reset() now takes a second parameter indicating whether we should reboot in HYP or not. Update the documentation to reflect this. Tested-by:
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Marc Zyngier authored
The conversion of the HYP stub ABI to something similar to arm64 left the KVM code broken, as it doesn't know about the new stub numbering. Let's move the various #defines to virt.h, and let KVM use HVC_GET_VECTORS. Tested-by:
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Russell King authored
When we soft-reboot (eg, kexec) from one kernel into the next, we need to ensure that we enter the new kernel in the same processor mode as when we were entered, so that (eg) the new kernel can install its own hypervisor - the old kernel's hypervisor will have been overwritten. In order to do this, we need to pass a flag to cpu_reset() so it knows what to do, and we need to modify the kernel's own hypervisor stub to allow it to handle a soft-reboot. As we are always guaranteed to install our own hypervisor if we're entered in HYP32 mode, and KVM will have moved itself out of the way on kexec/normal reboot, we can assume that our hypervisor is in place when we want to kexec, so changing our hypervisor API should not be a problem. Tested-by:
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Russell King authored
Improve the hyp-stub ABI to allow it to do more than just get/set the vectors. We follow the example in ARM64, where r0 is used as an opcode with the other registers as an argument. Tested-by:
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Marc Zyngier authored
Another missing stub hypercall is HVC_SOFT_RESTART. It turns out that it is pretty easy to implement in terms of HVC_RESET_VECTORS (since it needs to turn the MMU off). Acked-by:
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Marc Zyngier authored
We are now able to use the hyp stub to reset HYP mode. Time to kiss __kvm_hyp_reset goodbye, and use __hyp_reset_vectors. Acked-by:
James Morse <james.morse@arm.com> Signed-off-by:
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Marc Zyngier authored
We now have a full hyp-stub implementation in the KVM init code, but the main KVM code only supports HVC_GET_VECTORS, which is not enough. Instead of reinventing the wheel, let's reuse the init implementation by branching to the idmap page when called with a hyp-stub hypercall. Acked-by:
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Marc Zyngier authored
Now that we have an infrastructure to handle hypercalls in the KVM init code, let's implement HVC_GET_VECTORS there. Acked-by:
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Marc Zyngier authored
In order to restore HYP mode to its original condition, KVM currently implements __kvm_hyp_reset(). As we're moving towards a hyp-stub defined API, it becomes necessary to implement HVC_RESET_VECTORS. This patch adds the HVC_RESET_VECTORS hypercall to the KVM init code, which so far lacked any form of hypercall support. Acked-by:
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Marc Zyngier authored
Let's define a new stub hypercall that resets the HYP configuration to its default: hyp-stub vectors, and MMU disabled. Of course, for the hyp-stub itself, this is a trivial no-op. Hypervisors will have a bit more work to do. Acked-by:
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Marc Zyngier authored
Comments in asm/virt.h are slightly out of date, so let's align them with the new behaviour of the code. Signed-off-by:
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Marc Zyngier authored
Define a standard return value to be returned when a hyp stub call fails, and make KVM use it for ARM_EXCEPTION_HYP_GONE (instead of using a KVM-specific value). Signed-off-by:
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Marc Zyngier authored
The EL2 code is not corrupting lr anymore, so don't bother preserving it in the EL1 trampoline code. Acked-by:
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Marc Zyngier authored
At the moment, we only save/restore lr if on VHE, as we rely only the EL1 code to have preserved it in the non-VHE case. As we're about to get rid of the latter, let's move the save/restore code to the do_el2_call macro, unifying both code paths. Acked-by:
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Marc Zyngier authored
When entering the kernel hyp stub, we check whether or not we've made it here through an HVC instruction, clobbering lr (aka x30) in the process. This is completely pointless, as HVC is the only way to get here (all traps to EL2 are disabled, no interrupt override is applied). So let's remove this bit of code whose only point is to corrupt a valuable register. Acked-by:
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Marc Zyngier authored
Instead of considering that a CP15 accessor has failed when returning false, let's consider that it is *always* successful (after all, we won't stand for an incomplete emulation). The return value now simply indicates whether we should skip the instruction (because it has now been emulated), or if we should leave the PC alone if the emulation has injected an exception. Reviewed-by:
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Marc Zyngier authored
Reads from write-only system registers are generally confined to EL1 and not propagated to EL2 (that's what the architecture mantates). In order to be sure that we have a sane behaviour even in the unlikely event that we have a broken system, we still handle it in KVM. Same goes for write to RO registers. In that case, let's inject an undef into the guest. Reviewed-by:
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Marc Zyngier authored
If we fail to emulate a mrrc instruction, we: 1) deliver an exception, 2) spit a nastygram on the console, 3) write back some garbage to Rt/Rt2 While 1) and 2) are perfectly acceptable, 3) is out of the scope of the architecture... Let's mimick the code in kvm_handle_cp_32 and be more cautious. Reviewed-by:
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