Commit 45b890f7 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

Merge tag 'kvmarm-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD 

KVM/arm64 updates for 6.7

 - Generalized infrastructure for 'writable' ID registers, effectively
   allowing userspace to opt-out of certain vCPU features for its guest

 - Optimization for vSGI injection, opportunistically compressing MPIDR
   to vCPU mapping into a table

 - Improvements to KVM's PMU emulation, allowing userspace to select
   the number of PMCs available to a VM

 - Guest support for memory operation instructions (FEAT_MOPS)

 - Cleanups to handling feature flags in KVM_ARM_VCPU_INIT, squashing
   bugs and getting rid of useless code

 - Changes to the way the SMCCC filter is constructed, avoiding wasted
   memory allocations when not in use

 - Load the stage-2 MMU context at vcpu_load() for VHE systems, reducing
   the overhead of errata mitigations

 - Miscellaneous kernel and selftest fixes
parents be479419 123f42f0

Documentation/virt/kvm/api.rst

+52 −0
Original line number Diff line number Diff line
@@ -3422,6 +3422,8 @@ return indicates the attribute is implemented. It does not necessarily 
indicate that the attribute can be read or written in the device's

current state.  "addr" is ignored.



.. _KVM_ARM_VCPU_INIT:



4.82 KVM_ARM_VCPU_INIT

----------------------
@@ -6140,6 +6142,56 @@ writes to the CNTVCT_EL0 and CNTPCT_EL0 registers using the SET_ONE_REG 
interface. No error will be returned, but the resulting offset will not be

applied.



.. _KVM_ARM_GET_REG_WRITABLE_MASKS:



4.139 KVM_ARM_GET_REG_WRITABLE_MASKS

-------------------------------------------



:Capability: KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES

:Architectures: arm64

:Type: vm ioctl

:Parameters: struct reg_mask_range (in/out)

:Returns: 0 on success, < 0 on error





::



        #define KVM_ARM_FEATURE_ID_RANGE	0

        #define KVM_ARM_FEATURE_ID_RANGE_SIZE	(3 * 8 * 8)



        struct reg_mask_range {

                __u64 addr;             /* Pointer to mask array */

                __u32 range;            /* Requested range */

                __u32 reserved[13];

        };



This ioctl copies the writable masks for a selected range of registers to

userspace.



The ``addr`` field is a pointer to the destination array where KVM copies

the writable masks.



The ``range`` field indicates the requested range of registers.

``KVM_CHECK_EXTENSION`` for the ``KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES``

capability returns the supported ranges, expressed as a set of flags. Each

flag's bit index represents a possible value for the ``range`` field.

All other values are reserved for future use and KVM may return an error.



The ``reserved[13]`` array is reserved for future use and should be 0, or

KVM may return an error.



KVM_ARM_FEATURE_ID_RANGE (0)

^^^^^^^^^^^^^^^^^^^^^^^^^^^^



The Feature ID range is defined as the AArch64 System register space with

op0==3, op1=={0, 1, 3}, CRn==0, CRm=={0-7}, op2=={0-7}.



The mask returned array pointed to by ``addr`` is indexed by the macro

``ARM64_FEATURE_ID_RANGE_IDX(op0, op1, crn, crm, op2)``, allowing userspace

to know what fields can be changed for the system register described by

``op0, op1, crn, crm, op2``. KVM rejects ID register values that describe a

superset of the features supported by the system.



5. The kvm_run structure

========================

Documentation/virt/kvm/arm/index.rst

+1 −0
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@@ -11,3 +11,4 @@ ARM 
   hypercalls

   pvtime

   ptp_kvm

   vcpu-features

Documentation/virt/kvm/arm/vcpu-features.rst

0 → 100644
+48 −0
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.. SPDX-License-Identifier: GPL-2.0



===============================

vCPU feature selection on arm64

===============================



KVM/arm64 provides two mechanisms that allow userspace to configure

the CPU features presented to the guest.



KVM_ARM_VCPU_INIT

=================



The ``KVM_ARM_VCPU_INIT`` ioctl accepts a bitmap of feature flags

(``struct kvm_vcpu_init::features``). Features enabled by this interface are

*opt-in* and may change/extend UAPI. See :ref:`KVM_ARM_VCPU_INIT` for complete

documentation of the features controlled by the ioctl.



Otherwise, all CPU features supported by KVM are described by the architected

ID registers.



The ID Registers

================



The Arm architecture specifies a range of *ID Registers* that describe the set

of architectural features supported by the CPU implementation. KVM initializes

the guest's ID registers to the maximum set of CPU features supported by the

system. The ID register values may be VM-scoped in KVM, meaning that the

values could be shared for all vCPUs in a VM.



KVM allows userspace to *opt-out* of certain CPU features described by the ID

registers by writing values to them via the ``KVM_SET_ONE_REG`` ioctl. The ID

registers are mutable until the VM has started, i.e. userspace has called

``KVM_RUN`` on at least one vCPU in the VM. Userspace can discover what fields

are mutable in the ID registers using the ``KVM_ARM_GET_REG_WRITABLE_MASKS``.

See the :ref:`ioctl documentation <KVM_ARM_GET_REG_WRITABLE_MASKS>` for more

details.



Userspace is allowed to *limit* or *mask* CPU features according to the rules

outlined by the architecture in DDI0487J.a D19.1.3 'Principles of the ID

scheme for fields in ID register'. KVM does not allow ID register values that

exceed the capabilities of the system.



.. warning::

   It is **strongly recommended** that userspace modify the ID register values

   before accessing the rest of the vCPU's CPU register state. KVM may use the

   ID register values to control feature emulation. Interleaving ID register

   modification with other system register accesses may lead to unpredictable

   behavior.

Documentation/virt/kvm/devices/arm-vgic-v3.rst

+7 −0
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@@ -59,6 +59,13 @@ Groups: 
  It is invalid to mix calls with KVM_VGIC_V3_ADDR_TYPE_REDIST and

  KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION attributes.



  Note that to obtain reproducible results (the same VCPU being associated

  with the same redistributor across a save/restore operation), VCPU creation

  order, redistributor region creation order as well as the respective

  interleaves of VCPU and region creation MUST be preserved.  Any change in

  either ordering may result in a different vcpu_id/redistributor association,

  resulting in a VM that will fail to run at restore time.



  Errors:



    =======  =============================================================

arch/arm64/include/asm/kvm_arm.h

+3 −1
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@@ -102,7 +102,9 @@ 
#define HCR_HOST_NVHE_PROTECTED_FLAGS (HCR_HOST_NVHE_FLAGS | HCR_TSC)

#define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)



#define HCRX_GUEST_FLAGS (HCRX_EL2_SMPME | HCRX_EL2_TCR2En)

#define HCRX_GUEST_FLAGS \

	(HCRX_EL2_SMPME | HCRX_EL2_TCR2En | \

	 (cpus_have_final_cap(ARM64_HAS_MOPS) ? (HCRX_EL2_MSCEn | HCRX_EL2_MCE2) : 0))

#define HCRX_HOST_FLAGS (HCRX_EL2_MSCEn | HCRX_EL2_TCR2En)



/* TCR_EL2 Registers bits */