kernel/arch/arm64/kvm/sys_regs.h, branch linux-rolling-stable

KVM: arm64: Add timer UAPI workaround to sysreg infrastructure

2025-10-13T13:42:40Z

Amongst the numerous bugs that plague the KVM/arm64 UAPI, one of the most annoying thing is that the userspace view of the virtual timer has its CVAL and CNT encodings swapped. In order to reduce the amount of code that has to know about this, start by adding handling for this bug in the sys_reg code. Nothing is making use of it yet, as the code responsible for userspace interaction is catching the accesses early. Signed-off-by: Marc Zyngier

arm64: kvm: sys_regs: use string choices helper

2025-07-24T06:36:37Z

We can use string choices helper, let's use it. Signed-off-by: Kuninori Morimoto Link: https://lore.kernel.org/r/87pldy5ktb.wl-kuninori.morimoto.gx@renesas.com Signed-off-by: Oliver Upton

KVM: arm64: Add assignment-specific sysreg accessor

2025-06-05T13:17:32Z

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 Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20250603070824.1192795-2-maz@kernel.org Signed-off-by: Marc Zyngier

KVM: arm64: Make ID_REG_LIMIT_FIELD_ENUM() more widely available

2025-02-24T19:06:55Z

ID_REG_LIMIT_FIELD_ENUM() is a useful macro to limit the idreg features exposed to guest and userspace, and the NV code can make use of it. Signed-off-by: Marc Zyngier Reviewed-by: Joey Gouly Link: https://lore.kernel.org/r/20250220134907.554085-8-maz@kernel.org Signed-off-by: Oliver Upton

Merge branch kvm-arm64/visibility-cleanups into kvmarm-master/next

2024-09-12T07:38:17Z

* kvm-arm64/visibility-cleanups: : . : Remove REG_HIDDEN_USER from the sysreg infrastructure, making things : a little more simple. From the cover letter: : : "Since 4d4f52052ba8 ("KVM: arm64: nv: Drop EL12 register traps that are : redirected to VNCR") and the admission that KVM would never be supporting : the original FEAT_NV, REG_HIDDEN_USER only had a few users, all of which : could either be replaced by a more ad-hoc mechanism, or removed altogether." : . KVM: arm64: Get rid of REG_HIDDEN_USER visibility qualifier KVM: arm64: Simplify visibility handling of AArch32 SPSR_* KVM: arm64: Simplify handling of CNTKCTL_EL12 Signed-off-by: Marc Zyngier

KVM: arm64: Get rid of REG_HIDDEN_USER visibility qualifier

2024-09-11T18:50:43Z

Now that REG_HIDDEN_USER has no direct user anymore, remove it entirely and update all users of sysreg_hidden_user() to call sysreg_hidden() instead. Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20240904082419.1982402-4-maz@kernel.org Signed-off-by: Marc Zyngier

KVM: arm64: Make most GICv3 accesses UNDEF if they trap

2024-08-27T17:32:56Z

We don't expect to trap any GICv3 register for host handling, apart from ICC_SRE_EL1 and the SGI registers. If they trap, that's because the guest is playing with us despite being told it doesn't have a GICv3. If it does, UNDEF is what it will get. Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20240827152517.3909653-10-maz@kernel.org Signed-off-by: Marc Zyngier

KVM: arm64: Add helper for last ditch idreg adjustments

2024-08-27T17:32:55Z

We already have to perform a set of last-chance adjustments for NV purposes. We will soon have to do the same for the GIC, so introduce a helper for that exact purpose. Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20240827152517.3909653-5-maz@kernel.org Signed-off-by: Marc Zyngier

KVM: arm64: Rename __check_nv_sr_forward() to triage_sysreg_trap()

2024-02-19T17:13:01Z

__check_nv_sr_forward() is not specific to NV anymore, and does a lot more. Rename it to triage_sysreg_trap(), making it plain that its role is to handle where an exception is to be handled. Reviewed-by: Joey Gouly Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20240214131827.2856277-17-maz@kernel.org Signed-off-by: Oliver Upton

KVM: arm64: Save ID registers' sanitized value per guest

2023-06-15T12:55:08Z

Initialize the default ID register values upon the first call to KVM_ARM_VCPU_INIT. The vCPU feature flags are finalized at that point, so it is possible to determine the maximum feature set supported by a particular VM configuration. Do nothing with these values for now, as we need to rework the plumbing of what's already writable to be compatible with the generic infrastructure. Co-developed-by: Reiji Watanabe Signed-off-by: Reiji Watanabe Signed-off-by: Jing Zhang Link: https://lore.kernel.org/r/20230609190054.1542113-7-oliver.upton@linux.dev [Oliver: Hoist everything into KVM_ARM_VCPU_INIT time, so the features are final] Signed-off-by: Oliver Upton