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| author | Sean Christopherson <seanjc@google.com> | 2022-10-13 21:12:29 +0000 |
|---|---|---|
| committer | David Woodhouse <dwmw@amazon.co.uk> | 2022-11-30 19:25:24 +0000 |
| commit | 9f87791d686d85614584438d4f249eb32ef7964c (patch) | |
| tree | c2c4a01fd11883c843242ad0a3035fd7754809fa /include | |
| parent | 0318f207d1c2e297d1ec1c6e145bb8bd053236f9 (diff) | |
| download | linux-stable-9f87791d686d85614584438d4f249eb32ef7964c.tar.gz linux-stable-9f87791d686d85614584438d4f249eb32ef7964c.tar.bz2 linux-stable-9f87791d686d85614584438d4f249eb32ef7964c.zip | |
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 <seanjc@google.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/kvm_host.h | 12 |
1 files changed, 0 insertions, 12 deletions
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 @@ -1334,18 +1334,6 @@ 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. * * @gpc: struct gfn_to_pfn_cache object. |