kernel.git/arch/arm64/include/asm/kvm_nested.h, branch linux-6.10.y

KVM: arm64: nv: Add emulation for ERETAx instructions

2024-04-20T11:42:51Z

FEAT_NV has the interesting property of relying on ERET being trapped. An added complexity is that it also traps ERETAA and ERETAB, meaning that the Pointer Authentication aspect of these instruction must be emulated. Add an emulation of Pointer Authentication, limited to ERETAx (always using SP_EL2 as the modifier and ELR_EL2 as the pointer), using the Generic Authentication instructions. The emulation, however small, is placed in its own compilation unit so that it can be avoided if the configuration doesn't include it (or the toolchan in not up to the task). Reviewed-by: Joey Gouly Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20240419102935.1935571-13-maz@kernel.org Signed-off-by: Marc Zyngier

KVM: arm64: nv: Add trap forwarding for ERET and SMC

2024-04-20T11:42:50Z

Honor the trap forwarding bits for both ERET and SMC, using a new helper that checks for common conditions. Reviewed-by: Joey Gouly Co-developed-by: Jintack Lim Signed-off-by: Jintack Lim Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20240419102935.1935571-7-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: Use the xarray as the primary sysreg/sysinsn walker

2024-02-19T17:13:01Z

Since we always start sysreg/sysinsn handling by searching the xarray, use it as the source of the index in the correct sys_reg_desc array. This allows some cleanup, such as moving the handling of unknown sysregs in a single location. Reviewed-by: Joey Gouly Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20240214131827.2856277-16-maz@kernel.org Signed-off-by: Oliver Upton

KVM: arm64: nv: Add non-VHE-EL2->EL1 translation helpers

2023-12-19T09:51:11Z

Some EL2 system registers immediately affect the current execution of the system, so we need to use their respective EL1 counterparts. For this we need to define a mapping between the two. In general, this only affects non-VHE guest hypervisors, as VHE system registers are compatible with the EL1 counterparts. These helpers will get used in subsequent patches. Reviewed-by: Oliver Upton Co-developed-by: Andre Przywara Signed-off-by: Andre Przywara Signed-off-by: Marc Zyngier

KVM: arm64: nv: Compute NV view of idregs as a one-off

2023-12-19T09:51:00Z

Now that we have a full copy of the idregs for each VM, there is no point in repainting the sysregs on each access. Instead, we can simply perform the transmation as a one-off and be done with it. Reviewed-by: Oliver Upton Signed-off-by: Marc Zyngier

KVM: arm64: Get rid of vCPU-scoped feature bitmap

2023-09-21T18:13:29Z

The vCPU-scoped feature bitmap was left in place a couple of releases ago in case the change to VM-scoped vCPU features broke anyone. Nobody has complained and the interop between VM and vCPU bitmaps is pretty gross. Throw it out. Link: https://lore.kernel.org/r/20230920195036.1169791-9-oliver.upton@linux.dev Signed-off-by: Oliver Upton

KVM: arm64: nv: Add trap forwarding infrastructure

2023-08-17T09:00:27Z

A significant part of what a NV hypervisor needs to do is to decide whether a trap from a L2+ guest has to be forwarded to a L1 guest or handled locally. This is done by checking for the trap bits that the guest hypervisor has set and acting accordingly, as described by the architecture. A previous approach was to sprinkle a bunch of checks in all the system register accessors, but this is pretty error prone and doesn't help getting an overview of what is happening. Instead, implement a set of global tables that describe a trap bit, combinations of trap bits, behaviours on trap, and what bits must be evaluated on a system register trap. Although this is painful to describe, this allows to specify each and every control bit in a static manner. To make it efficient, the table is inserted in an xarray that is global to the system, and checked each time we trap a system register while running a L2 guest. Add the basic infrastructure for now, while additional patches will implement configuration registers. Signed-off-by: Marc Zyngier Reviewed-by: Jing Zhang Reviewed-by: Miguel Luis Link: https://lore.kernel.org/r/20230815183903.2735724-15-maz@kernel.org

KVM: arm64: nv: Filter out unsupported features from ID regs

2023-02-11T10:13:30Z

As there is a number of features that we either can't support, or don't want to support right away with NV, let's add some basic filtering so that we don't advertize silly things to the EL2 guest. Whilst we are at it, advertize FEAT_TTL as well as FEAT_GTG, which the NV implementation will implement. Reviewed-by: Ganapatrao Kulkarni Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230209175820.1939006-18-maz@kernel.org Signed-off-by: Oliver Upton

KVM: arm64: nv: Introduce nested virtualization VCPU feature

2023-02-11T09:16:11Z

Introduce the feature bit and a primitive that checks if the feature is set behind a static key check based on the cpus_have_const_cap check. Checking vcpu_has_nv() on systems without nested virt enabled should have negligible overhead. We don't yet allow userspace to actually set this feature. Reviewed-by: Ganapatrao Kulkarni Reviewed-by: Russell King (Oracle) Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20230209175820.1939006-4-maz@kernel.org Signed-off-by: Oliver Upton