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In a number of cases, we perform a Read-Modify-Write operation on
a system register, meaning that we would apply the RESx masks twice.
Instead, provide a new accessor that performs this RMW operation,
allowing the masks to be applied exactly once per operation.
Reviewed-by: Miguel Luis <miguel.luis@oracle.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250603070824.1192795-3-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Assigning a value to a system register doesn't do what it is
supposed to be doing if that register is one that has RESx bits.
The main problem is that we use __vcpu_sys_reg(), which can be used
both as a lvalue and rvalue. When used as a lvalue, the bit masking
occurs *before* the new value is assigned, meaning that we (1) do
pointless work on the old cvalue, and (2) potentially assign an
invalid value as we fail to apply the masks to it.
Fix this by providing a new __vcpu_assign_sys_reg() that does
what it says on the tin, and sanitises the *new* value instead of
the old one. This comes with a significant amount of churn.
Reviewed-by: Miguel Luis <miguel.luis@oracle.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20250603070824.1192795-2-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Userspace will soon be able to change the value of MIDR_EL1. Prepare by
loading VPIDR_EL2 with the guest value for non-nested VMs.
Since VPIDR_EL2 is set for any VM, get rid of the NV-specific cleanup of
reloading the hardware value on vcpu_put(). And for nVHE, load the
hardware value before switching to the host.
Link: https://lore.kernel.org/r/20250225005401.679536-4-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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A lot of the NV code depends on HCR_EL2.{E2H,TGE}, and we assume
in places that at least HCR_EL2.E2H is invariant for a given guest.
However, we make a point in *not* using the sanitising accessor
that would enforce this, and are at the mercy of the guest doing
stupid things. Clearly, that's not good.
Rework the HCR_EL2 accessors to use __vcpu_sys_reg() instead,
guaranteeing that the RESx settings get applied, specially
when HCR_EL2.E2H is evaluated. This results in fewer accessors
overall.
Huge thanks to Joey who spent a long time tracking this bug down.
Reported-by: Joey Gouly <Joey.Gouly@arm.com>
Tested-by: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20250112165029.1181056-2-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
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POR_EL2 needs saving when the guest is VHE, and restoring in
any case.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241023145345.1613824-33-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Like their EL1 equivalent, the EL2-specific FEAT_S1PIE registers
are context-switched. This is made conditional on both FEAT_TCRX
and FEAT_S1PIE being adversised.
Note that this change only makes sense if read together with the
issue D22677 contained in 102105_K.a_04_en.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241023145345.1613824-16-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Like its EL1 equivalent, TCR2_EL2 gets context-switched.
This is made conditional on FEAT_TCRX being adversised.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241023145345.1613824-14-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Whenever we need to restore the guest's system registers to the CPU, we
now need to take care of the EL2 system registers as well. Most of them
are accessed via traps only, but some have an immediate effect and also
a guest running in VHE mode would expect them to be accessible via their
EL1 encoding, which we do not trap.
For vEL2 we write the virtual EL2 registers with an identical format directly
into their EL1 counterpart, and translate the few registers that have a
different format for the same effect on the execution when running a
non-VHE guest guest hypervisor.
Based on an initial patch from Andre Przywara, rewritten many times
since.
Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241023145345.1613824-8-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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In order to facilitate the introduction of new per-CPU state,
add a new host_data_ptr() helped that hides some of the per-CPU
verbosity, and make it easier to move that state around in the
future.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Use the correct function name in the kernel-doc comment to prevent
a warning:
arch/arm64/kvm/hyp/vhe/sysreg-sr.c:109: warning: expecting prototype for __vcpu_put_switch_syregs(). Prototype was for __vcpu_put_switch_sysregs() instead
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Zenghui Yu <yuzenghui@huawei.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.linux.dev
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20240117230714.31025-5-rdunlap@infradead.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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The names for the helpers we expose to the 'generic' KVM code are a bit
imprecise; we switch the EL0 + EL1 sysreg context and setup trap
controls that do not need to change for every guest entry/exit. Rename +
shuffle things around a bit in preparation for loading the stage-2 MMU
context on vcpu_load().
Link: https://lore.kernel.org/r/20231018233212.2888027-5-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Contrary to nVHE, VHE is a lot easier when it comes to dealing
with speculative page table walks started at EL1. As we only change
EL1&0 translation regime when context-switching, we already benefit
from the effect of the DSB that sits in the context switch code.
We only need to take care of it in the NV case, where we can
flip between between two EL1 contexts (one of them being the virtual
EL2) without a context switch.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
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The aptly named boolean 'sysregs_loaded_on_cpu' tracks whether
some of the vcpu system registers are resident on the physical
CPU when running in VHE mode.
This is obviously a flag in hidding, so let's convert it to
a state flag, since this is solely a host concern (the hypervisor
itself always knows which state we're in).
Reviewed-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
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On deactivating traps, restore the value of mdcr_el2 from the
newly created and preserved host value vcpu context, rather than
directly reading the hardware register.
Up until and including this patch the two values are the same,
i.e., the hardware register and the vcpu one. A future patch will
be changing the value of mdcr_el2 on activating traps, and this
ensures that its value will be restored.
No functional change intended.
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210817081134.2918285-7-tabba@google.com
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this_cpu_ptr is meant for use in kernel proper because it selects between
TPIDR_EL1/2 based on nVHE/VHE. __hyp_this_cpu_ptr was used in hyp to always
select TPIDR_EL2. Unify all users behind this_cpu_ptr and friends by
selecting _EL2 register under __KVM_NVHE_HYPERVISOR__. VHE continues
selecting the register using alternatives.
Under CONFIG_DEBUG_PREEMPT, the kernel helpers perform a preemption check
which is omitted by the hyp helpers. Preserve the behavior for nVHE by
overriding the corresponding macros under __KVM_NVHE_HYPERVISOR__. Extend
the checks into VHE hyp code.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Andrew Scull <ascull@google.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200922204910.7265-5-dbrazdil@google.com
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sysreg-sr.c contains KVM's code for saving/restoring system registers, with
some code shared between VHE/nVHE. These common routines are moved to
a header file, VHE-specific code is moved to vhe/sysreg-sr.c and nVHE-specific
code to nvhe/sysreg-sr.c.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-12-dbrazdil@google.com
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