KVM: Remove unnecessary divide operations
This patch converts unnecessary divide and modulo operations
in the KVM large page related code into logical operations.
This allows to convert gfn_t to u64 while not breaking 32
bit builds.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
index a362e67..2f229e5 100644
--- a/arch/ia64/include/asm/kvm_host.h
+++ b/arch/ia64/include/asm/kvm_host.h
@@ -235,6 +235,7 @@
#define KVM_REQ_PTC_G 32
#define KVM_REQ_RESUME 33
+#define KVM_HPAGE_GFN_SHIFT(x) 0
#define KVM_NR_PAGE_SIZES 1
#define KVM_PAGES_PER_HPAGE(x) 1
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index e004eaf..b0b23c0 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -35,6 +35,7 @@
#define KVM_COALESCED_MMIO_PAGE_OFFSET 1
/* We don't currently support large pages. */
+#define KVM_HPAGE_GFN_SHIFT(x) 0
#define KVM_NR_PAGE_SIZES 1
#define KVM_PAGES_PER_HPAGE(x) (1UL<<31)
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index b95710a..cef7dbf 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -41,7 +41,8 @@
} __attribute__((packed));
#define KVM_NR_PAGE_SIZES 2
-#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + ((x) - 1) * 8)
+#define KVM_HPAGE_GFN_SHIFT(x) (((x) - 1) * 8)
+#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + KVM_HPAGE_GFN_SHIFT(x))
#define KVM_HPAGE_SIZE(x) (1UL << KVM_HPAGE_SHIFT(x))
#define KVM_HPAGE_MASK(x) (~(KVM_HPAGE_SIZE(x) - 1))
#define KVM_PAGES_PER_HPAGE(x) (KVM_HPAGE_SIZE(x) / PAGE_SIZE)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2bda624..50c79b9 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -44,7 +44,8 @@
/* KVM Hugepage definitions for x86 */
#define KVM_NR_PAGE_SIZES 3
-#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + (((x) - 1) * 9))
+#define KVM_HPAGE_GFN_SHIFT(x) (((x) - 1) * 9)
+#define KVM_HPAGE_SHIFT(x) (PAGE_SHIFT + KVM_HPAGE_GFN_SHIFT(x))
#define KVM_HPAGE_SIZE(x) (1UL << KVM_HPAGE_SHIFT(x))
#define KVM_HPAGE_MASK(x) (~(KVM_HPAGE_SIZE(x) - 1))
#define KVM_PAGES_PER_HPAGE(x) (KVM_HPAGE_SIZE(x) / PAGE_SIZE)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ca07ed0..a20fd61 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -423,8 +423,8 @@
{
unsigned long idx;
- idx = (gfn / KVM_PAGES_PER_HPAGE(level)) -
- (slot->base_gfn / KVM_PAGES_PER_HPAGE(level));
+ idx = (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
+ (slot->base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
return &slot->lpage_info[level - 2][idx].write_count;
}
@@ -528,8 +528,8 @@
if (likely(level == PT_PAGE_TABLE_LEVEL))
return &slot->rmap[gfn - slot->base_gfn];
- idx = (gfn / KVM_PAGES_PER_HPAGE(level)) -
- (slot->base_gfn / KVM_PAGES_PER_HPAGE(level));
+ idx = (gfn >> KVM_HPAGE_GFN_SHIFT(level)) -
+ (slot->base_gfn >> KVM_HPAGE_GFN_SHIFT(level));
return &slot->lpage_info[level - 2][idx].rmap_pde;
}