From 9f87791d686d85614584438d4f249eb32ef7964c Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 13 Oct 2022 21:12:29 +0000 Subject: KVM: Drop KVM's API to allow temporarily unmapping gfn=>pfn cache Drop kvm_gpc_unmap() as it has no users and unclear requirements. The API was added as part of the original gfn_to_pfn_cache support, but its sole usage[*] was never merged. Fold the guts of kvm_gpc_unmap() into the deactivate path and drop the API. Omit acquiring refresh_lock as as concurrent calls to kvm_gpc_deactivate() are not allowed (this is not enforced, e.g. via lockdep. due to it being called during vCPU destruction). If/when temporary unmapping makes a comeback, the desirable behavior is likely to restrict temporary unmapping to vCPU-exclusive mappings and require the vcpu->mutex be held to serialize unmap. Use of the refresh_lock to protect unmapping was somewhat specuatively added by commit 93984f19e7bc ("KVM: Fully serialize gfn=>pfn cache refresh via mutex") to guard against concurrent unmaps, but the primary use case of the temporary unmap, nested virtualization[*], doesn't actually need or want concurrent unmaps. [*] https://lore.kernel.org/all/20211210163625.2886-7-dwmw2@infradead.org Signed-off-by: Sean Christopherson Signed-off-by: David Woodhouse --- include/linux/kvm_host.h | 12 ------------ 1 file changed, 12 deletions(-) (limited to 'include/linux') diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 3ce4650776b8..eac76965cf44 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1333,18 +1333,6 @@ bool kvm_gpc_check(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len); */ int kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len); -/** - * kvm_gpc_unmap - temporarily unmap a gfn_to_pfn_cache. - * - * @kvm: pointer to kvm instance. - * @gpc: struct gfn_to_pfn_cache object. - * - * This unmaps the referenced page. The cache is left in the invalid state - * but at least the mapping from GPA to userspace HVA will remain cached - * and can be reused on a subsequent refresh. - */ -void kvm_gpc_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc); - /** * kvm_gpc_deactivate - deactivate and unlink a gfn_to_pfn_cache. * -- cgit v1.2.3