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Commit 82855413 authored by Joerg Roedel's avatar Joerg Roedel Committed by Avi Kivity
Browse files

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: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 95c87e2b

arch/ia64/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -235,6 +235,7 @@ struct kvm_vm_data { 
#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

arch/powerpc/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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)

arch/s390/include/asm/kvm_host.h

+2 −1
Original line number Diff line number Diff line
@@ -41,7 +41,8 @@ struct sca_block { 
} __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)

arch/x86/include/asm/kvm_host.h

+2 −1
Original line number Diff line number Diff line
@@ -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)

arch/x86/kvm/mmu.c

+4 −4
Original line number Diff line number Diff line
@@ -423,8 +423,8 @@ static int *slot_largepage_idx(gfn_t gfn, 
{

	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 @@ static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, int level) 
	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;

}