From f55ce5a6cd33211c8cc5bce0554b6ac710a6a28b Mon Sep 17 00:00:00 2001 From: Ankit Agrawal Date: Sat, 5 Jul 2025 07:17:17 +0000 Subject: 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 CC: Jason Gunthorpe CC: Oliver Upton CC: David Hildenbrand Suggested-by: Marc Zyngier Reviewed-by: Jason Gunthorpe Tested-by: Donald Dutile Signed-off-by: Ankit Agrawal Reviewed-by: Catalin Marinas Link: https://lore.kernel.org/r/20250705071717.5062-7-ankita@nvidia.com Signed-off-by: Oliver Upton --- include/uapi/linux/kvm.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 37891580d05d..e4e566ff348b 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -956,6 +956,7 @@ struct kvm_enable_cap { #define KVM_CAP_ARM_EL2 240 #define KVM_CAP_ARM_EL2_E2H0 241 #define KVM_CAP_RISCV_MP_STATE_RESET 242 +#define KVM_CAP_ARM_CACHEABLE_PFNMAP_SUPPORTED 243 struct kvm_irq_routing_irqchip { __u32 irqchip; -- cgit v1.2.3