From dfd4eb444e5cef4387605d1eef1866ceea0544ce Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 12 Jul 2022 02:07:24 +0000 Subject: KVM: x86/mmu: Fix typo and tweak comment for split_desc_cache capacity Remove a spurious closing paranthesis and tweak the comment about the cache capacity for PTE descriptors (rmaps) eager page splitting to tone down the assertion slightly, and to call out that topup requires dropping mmu_lock, which is the real motivation for avoiding topup (as opposed to memory usage). Cc: David Matlack Signed-off-by: Sean Christopherson Message-Id: <20220712020724.1262121-4-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'arch/x86/kvm') diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 7a65e57b9b41..52664c3caaab 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6125,14 +6125,15 @@ static int topup_split_caches(struct kvm *kvm) { /* * Allocating rmap list entries when splitting huge pages for nested - * MMUs is uncommon as KVM needs to allocate if and only if there is + * MMUs is uncommon as KVM needs to use a list if and only if there is * more than one rmap entry for a gfn, i.e. requires an L1 gfn to be - * aliased by multiple L2 gfns. Aliasing gfns when using TDP is very - * atypical for VMMs; a few gfns are often aliased during boot, e.g. - * when remapping firmware, but aliasing rarely occurs post-boot). If - * there is only one rmap entry, rmap->val points directly at that one - * entry and doesn't need to allocate a list. Buffer the cache by the - * default capacity so that KVM doesn't have to topup the cache if it + * aliased by multiple L2 gfns and/or from multiple nested roots with + * different roles. Aliasing gfns when using TDP is atypical for VMMs; + * a few gfns are often aliased during boot, e.g. when remapping BIOS, + * but aliasing rarely occurs post-boot or for many gfns. If there is + * only one rmap entry, rmap->val points directly at that one entry and + * doesn't need to allocate a list. Buffer the cache by the default + * capacity so that KVM doesn't have to drop mmu_lock to topup if KVM * encounters an aliased gfn or two. */ const int capacity = SPLIT_DESC_CACHE_MIN_NR_OBJECTS + -- cgit v1.2.3