linux-toradex.git/arch/arm64/kvm/debug.c, branch v5.18

KVM: arm64: Emulate the OS Lock

2022-02-08T14:23:41+00:00

The OS lock blocks all debug exceptions at every EL. To date, KVM has
not implemented the OS lock for its guests, despite the fact that it is
mandatory per the architecture. Simple context switching between the
guest and host is not appropriate, as its effects are not constrained to
the guest context.

Emulate the OS Lock by clearing MDE and SS in MDSCR_EL1, thereby
blocking all but software breakpoint instructions.

Signed-off-by: Oliver Upton 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220203174159.2887882-5-oupton@google.com

KVM: arm64: MDCR_EL2 is a 64-bit register

2021-08-20T10:12:17+00:00

Fix the places in KVM that treat MDCR_EL2 as a 32-bit register.
More recent features (e.g., FEAT_SPEv1p2) use bits above 31.

No functional change intended.

Acked-by: Will Deacon 
Signed-off-by: Fuad Tabba 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20210817081134.2918285-4-tabba@google.com

Merge branch 'kvm-arm64/debug-5.13' into kvmarm-master/next

2021-04-13T14:34:15+00:00

Signed-off-by: Marc Zyngier

KVM: arm64: Initialize VCPU mdcr_el2 before loading it

2021-04-07T15:40:03+00:00

When a VCPU is created, the kvm_vcpu struct is initialized to zero in
kvm_vm_ioctl_create_vcpu(). On VHE systems, the first time
vcpu.arch.mdcr_el2 is loaded on hardware is in vcpu_load(), before it is
set to a sensible value in kvm_arm_setup_debug() later in the run loop. The
result is that KVM executes for a short time with MDCR_EL2 set to zero.

This has several unintended consequences:

* Setting MDCR_EL2.HPMN to 0 is constrained unpredictable according to ARM
  DDI 0487G.a, page D13-3820. The behavior specified by the architecture
  in this case is for the PE to behave as if MDCR_EL2.HPMN is set to a
  value less than or equal to PMCR_EL0.N, which means that an unknown
  number of counters are now disabled by MDCR_EL2.HPME, which is zero.

* The host configuration for the other debug features controlled by
  MDCR_EL2 is temporarily lost. This has been harmless so far, as Linux
  doesn't use the other fields, but that might change in the future.

Let's avoid both issues by initializing the VCPU's mdcr_el2 field in
kvm_vcpu_vcpu_first_run_init(), thus making sure that the MDCR_EL2 register
has a consistent value after each vcpu_load().

Fixes: d5a21bcc2995 ("KVM: arm64: Move common VHE/non-VHE trap config in separate functions")
Signed-off-by: Alexandru Elisei 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20210407144857.199746-3-alexandru.elisei@arm.com

arm64: KVM: Enable access to TRBE support for host

2021-04-06T22:05:28+00:00

For a nvhe host, the EL2 must allow the EL1&0 translation
regime for TraceBuffer (MDCR_EL2.E2TB == 0b11). This must
be saved/restored over a trip to the guest. Also, before
entering the guest, we must flush any trace data if the
TRBE was enabled. And we must prohibit the generation
of trace while we are in EL1 by clearing the TRFCR_EL1.

For vhe, the EL2 must prevent the EL1 access to the Trace
Buffer.

The MDCR_EL2 bit definitions for TRBE are available here :

  https://developer.arm.com/documentation/ddi0601/2020-12/AArch64-Registers/

Cc: Will Deacon 
Cc: Catalin Marinas 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Cc: Anshuman Khandual 
Signed-off-by: Suzuki K Poulose 
Acked-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20210405164307.1720226-8-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier

KVM: arm64: Move SPE availability check to VCPU load

2021-04-06T22:05:20+00:00

At the moment, we check the availability of SPE on the given
CPU (i.e, SPE is implemented and is allowed at the host) during
every guest entry. This can be optimized a bit by moving the
check to vcpu_load time and recording the availability of the
feature on the current CPU via a new flag. This will also be useful
for adding the TRBE support.

Cc: Marc Zyngier 
Cc: Will Deacon 
Cc: Alexandru Elisei 
Cc: James Morse 
Signed-off-by: Suzuki K Poulose 
Acked-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20210405164307.1720226-7-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier

KVM: arm64: Disable guest access to trace filter controls

2021-03-24T17:26:38+00:00

Disable guest access to the Trace Filter control registers.
We do not advertise the Trace filter feature to the guest
(ID_AA64DFR0_EL1: TRACE_FILT is cleared) already, but the guest
can still access the TRFCR_EL1 unless we trap it.

This will also make sure that the guest cannot fiddle with
the filtering controls set by a nvhe host.

Cc: Marc Zyngier 
Cc: Will Deacon 
Cc: Mark Rutland 
Cc: Catalin Marinas 
Signed-off-by: Suzuki K Poulose 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20210323120647.454211-3-suzuki.poulose@arm.com

KVM: arm64: Write arch.mdcr_el2 changes since last vcpu_load on VHE

2020-01-22T18:38:04+00:00

On VHE systems arch.mdcr_el2 is written to mdcr_el2 at vcpu_load time to
set options for self-hosted debug and the performance monitors
extension.

Unfortunately the value of arch.mdcr_el2 is not calculated until
kvm_arm_setup_debug() in the run loop after the vcpu has been loaded.
This means that the initial brief iterations of the run loop use a zero
value of mdcr_el2 - until the vcpu is preempted. This also results in a
delay between changes to vcpu->guest_debug taking effect.

Fix this by writing to mdcr_el2 in kvm_arm_setup_debug() on VHE systems
when a change to arch.mdcr_el2 has been detected.

Fixes: d5a21bcc2995 ("KVM: arm64: Move common VHE/non-VHE trap config in separate functions")
Cc:  # 4.17.x-
Suggested-by: James Morse 
Acked-by: Will Deacon 
Reviewed-by: Marc Zyngier 
Signed-off-by: Andrew Murray 
Signed-off-by: Catalin Marinas

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234

2019-06-19T15:09:07+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation this program is
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details you should have received a copy of the gnu general
  public license along with this program if not see http www gnu org
  licenses

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 503 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Alexios Zavras 
Reviewed-by: Allison Randal 
Reviewed-by: Enrico Weigelt 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman

arm/arm64: KVM: Introduce kvm_call_hyp_ret()

2019-02-19T21:05:24+00:00

Until now, we haven't differentiated between HYP calls that
have a return value and those who don't. As we're about to
change this, introduce kvm_call_hyp_ret(), and change all
call sites that actually make use of a return value.

Signed-off-by: Marc Zyngier 
Acked-by: Christoffer Dall 
Signed-off-by: Christoffer Dall