diff options
| author | Ankit Agrawal <ankita@nvidia.com> | 2025-07-05 07:17:17 +0000 |
|---|---|---|
| committer | Oliver Upton <oliver.upton@linux.dev> | 2025-07-07 16:54:52 -0700 |
| commit | f55ce5a6cd33211c8cc5bce0554b6ac710a6a28b (patch) | |
| tree | 23ae65ba8726c4529c9d4b9d8ac168ec6effca60 /Documentation/virt/kvm/api.rst | |
| parent | 0c67288e0c8bc1e39d7057fbae65bf57ca943676 (diff) | |
KVM: arm64: Expose new KVM cap for cacheable PFNMAP
Introduce a new KVM capability to expose to the userspace whether
cacheable mapping of PFNMAP is supported.
The ability to safely do the cacheable mapping of PFNMAP is contingent
on S2FWB and ARM64_HAS_CACHE_DIC. S2FWB allows KVM to avoid flushing
the D cache, ARM64_HAS_CACHE_DIC allows KVM to avoid flushing the icache
and turns icache_inval_pou() into a NOP. The cap would be false if
those requirements are missing and is checked by making use of
kvm_arch_supports_cacheable_pfnmap.
This capability would allow userspace to discover the support.
It could for instance be used by userspace to prevent live-migration
across FWB and non-FWB hosts.
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Jason Gunthorpe <jgg@nvidia.com>
CC: Oliver Upton <oliver.upton@linux.dev>
CC: David Hildenbrand <david@redhat.com>
Suggested-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Donald Dutile <ddutile@redhat.com>
Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20250705071717.5062-7-ankita@nvidia.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Diffstat (limited to 'Documentation/virt/kvm/api.rst')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 9abf93ee5f65..53e0179d5294 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8585,7 +8585,7 @@ ENOSYS for the others. When enabled, KVM will exit to userspace with KVM_EXIT_SYSTEM_EVENT of type KVM_SYSTEM_EVENT_SUSPEND to process the guest suspend request. -7.37 KVM_CAP_ARM_WRITABLE_IMP_ID_REGS +7.42 KVM_CAP_ARM_WRITABLE_IMP_ID_REGS ------------------------------------- :Architectures: arm64 @@ -8614,6 +8614,17 @@ given VM. When this capability is enabled, KVM resets the VCPU when setting MP_STATE_INIT_RECEIVED through IOCTL. The original MP_STATE is preserved. +7.43 KVM_CAP_ARM_CACHEABLE_PFNMAP_SUPPORTED +------------------------------------------- + +:Architectures: arm64 +:Target: VM +:Parameters: None + +This capability indicate to the userspace whether a PFNMAP memory region +can be safely mapped as cacheable. This relies on the presence of +force write back (FWB) feature support on the hardware. + 8. Other capabilities. ====================== |