lkml.org 
[lkml]   [2016]   [Mar]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3/4] KVM: MMU: reduce the size of mmu_page_path
Date
Currently only PT64_ROOT_LEVEL - 1 levels are used, one additional entry
in .parent[] is used as a sentinel, the additional entry in .idx[] is
purely wasted

This patch reduces its size and sets the sentinel on the upper level of
the place where we start from

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
arch/x86/kvm/mmu.c | 32 ++++++++++++--------------------
1 file changed, 12 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e273144..c396e8b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1984,12 +1984,12 @@ static bool kvm_sync_pages(struct kvm_vcpu *vcpu, gfn_t gfn,
}

struct mmu_page_path {
- struct kvm_mmu_page *parent[PT64_ROOT_LEVEL];
- unsigned int idx[PT64_ROOT_LEVEL];
+ struct kvm_mmu_page *parent[PT64_ROOT_LEVEL - 1];
+ unsigned int idx[PT64_ROOT_LEVEL - 1];
};

#define for_each_sp(pvec, sp, parents, i) \
- for (i = mmu_pages_first(&pvec, &parents); \
+ for (i = mmu_pages_next(&pvec, &parents, -1); \
i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \
i = mmu_pages_next(&pvec, &parents, i))

@@ -2016,25 +2016,15 @@ static int mmu_pages_next(struct kvm_mmu_pages *pvec,
return n;
}

-static int mmu_pages_first(struct kvm_mmu_pages *pvec,
- struct mmu_page_path *parents)
+static void
+mmu_pages_init(struct mmu_page_path *parents, struct kvm_mmu_page *parent)
{
- struct kvm_mmu_page *sp;
- int level;
-
- if (pvec->nr == 0)
- return 0;
-
- sp = pvec->page[0].sp;
- level = sp->role.level;
- WARN_ON(level == PT_PAGE_TABLE_LEVEL);
-
/*
- * Also set up a sentinel. Further entries in pvec are all
- * children of sp, so this element is never overwritten.
+ * set up a sentinel. Further entries in pvec are all children of
+ * sp, so this element is never overwritten.
*/
- parents->parent[level - 1] = NULL;
- return mmu_pages_next(pvec, parents, -1);
+ if (parent->role.level < PT64_ROOT_LEVEL)
+ parents->parent[parent->role.level - 1] = NULL;
}

static void mmu_pages_clear_parents(struct mmu_page_path *parents)
@@ -2051,7 +2041,7 @@ static void mmu_pages_clear_parents(struct mmu_page_path *parents)
WARN_ON(idx == INVALID_INDEX);
clear_unsync_child_bit(sp, idx);
level++;
- } while (!sp->unsync_children);
+ } while (!sp->unsync_children && (level < PT64_ROOT_LEVEL - 1));
}

static void mmu_sync_children(struct kvm_vcpu *vcpu,
@@ -2064,6 +2054,7 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
LIST_HEAD(invalid_list);
bool flush = false;

+ mmu_pages_init(&parents, parent);
while (mmu_unsync_walk(parent, &pages)) {
bool protected = false;

@@ -2335,6 +2326,7 @@ static int mmu_zap_unsync_children(struct kvm *kvm,
if (parent->role.level == PT_PAGE_TABLE_LEVEL)
return 0;

+ mmu_pages_init(&parents, parent);
while (mmu_unsync_walk(parent, &pages)) {
struct kvm_mmu_page *sp;

--
1.8.3.1
\
 
 \ /
  Last update: 2016-03-25 15:21    [W:0.210 / U:0.708 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site