55 lines
1.9 KiB
Diff
55 lines
1.9 KiB
Diff
From: Wei Yang <richard.weiyang@gmail.com>
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Date: Thu, 6 Sep 2018 05:58:16 +0800
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Subject: KVM: x86: adjust kvm_mmu_page member to save 8 bytes
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commit 3ff519f29d98ecdc1961d825d105d68711093b6b upstream.
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On a 64bits machine, struct is naturally aligned with 8 bytes. Since
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kvm_mmu_page member *unsync* and *role* are less then 4 bytes, we can
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rearrange the sequence to compace the struct.
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As the comment shows, *role* and *gfn* are used to key the shadow page. In
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order to keep the comment valid, this patch moves the *unsync* up and
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exchange the position of *role* and *gfn*.
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From /proc/slabinfo, it shows the size of kvm_mmu_page is 8 bytes less and
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with one more object per slap after applying this patch.
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# name <active_objs> <num_objs> <objsize> <objperslab>
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kvm_mmu_page_header 0 0 168 24
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kvm_mmu_page_header 0 0 160 25
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Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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---
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arch/x86/include/asm/kvm_host.h | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
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index 0d3f5cf3ff3e..90dccb5c79d9 100644
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--- a/arch/x86/include/asm/kvm_host.h
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+++ b/arch/x86/include/asm/kvm_host.h
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@@ -281,18 +281,18 @@ struct kvm_rmap_head {
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struct kvm_mmu_page {
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struct list_head link;
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struct hlist_node hash_link;
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+ bool unsync;
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/*
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* The following two entries are used to key the shadow page in the
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* hash table.
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*/
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- gfn_t gfn;
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union kvm_mmu_page_role role;
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+ gfn_t gfn;
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u64 *spt;
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/* hold the gfn of each spte inside spt */
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gfn_t *gfns;
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- bool unsync;
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int root_count; /* Currently serving as active root */
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unsigned int unsync_children;
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struct kvm_rmap_head parent_ptes; /* rmap pointers to parent sptes */
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