diff options
| author | Sean Christopherson <sean.j.christopherson@intel.com> | 2019-09-12 19:46:11 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-09-24 14:36:00 +0200 |
| commit | ca333add6933ad9732ba2c6671f133d7367ad96c (patch) | |
| tree | 87f67f03465469591eda96f3534673ea874471fd /arch/x86/include/asm | |
| parent | 10605204e91f46bdec98bef81923263d245515a0 (diff) | |
KVM: x86/mmu: Explicitly track only a single invalid mmu generation
Toggle mmu_valid_gen between '0' and '1' instead of blindly incrementing
the generation. Because slots_lock is held for the entire duration of
zapping obsolete pages, it's impossible for there to be multiple invalid
generations associated with shadow pages at any given time.
Toggling between the two generations (valid vs. invalid) allows changing
mmu_valid_gen from an unsigned long to a u8, which reduces the size of
struct kvm_mmu_page from 160 to 152 bytes on 64-bit KVM, i.e. reduces
KVM's memory footprint by 8 bytes per shadow page.
Set sp->mmu_valid_gen before it is added to active_mmu_pages.
Functionally this has no effect as kvm_mmu_alloc_page() has a single
caller that sets sp->mmu_valid_gen soon thereafter, but visually it is
jarring to see a shadow page being added to the list without its
mmu_valid_gen first being set.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 53e0b956ed3c..c5ed92482e2c 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -320,6 +320,7 @@ struct kvm_mmu_page { struct list_head link; struct hlist_node hash_link; bool unsync; + u8 mmu_valid_gen; bool mmio_cached; /* @@ -335,7 +336,6 @@ struct kvm_mmu_page { int root_count; /* Currently serving as active root */ unsigned int unsync_children; struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */ - unsigned long mmu_valid_gen; DECLARE_BITMAP(unsync_child_bitmap, 512); #ifdef CONFIG_X86_32 @@ -859,7 +859,7 @@ struct kvm_arch { unsigned long n_requested_mmu_pages; unsigned long n_max_mmu_pages; unsigned int indirect_shadow_pages; - unsigned long mmu_valid_gen; + u8 mmu_valid_gen; struct hlist_head mmu_page_hash[KVM_NUM_MMU_PAGES]; /* * Hash table of struct kvm_mmu_page. |