Patchwork [v3] KVM: Move gfn_to_memslot() to kvm_host.h

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Submitter Paul Mackerras
Date Jan. 13, 2012, 6:09 a.m.
Message ID <20120113060951.GB15875@drongo>
Download mbox | patch
Permalink /patch/135718/
State New
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Comments

Paul Mackerras - Jan. 13, 2012, 6:09 a.m.
This moves __gfn_to_memslot() and search_memslots() from kvm_main.c to
kvm_host.h to reduce the code duplication caused by the need for
non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c to call
gfn_to_memslot() in real mode.

Rather than putting gfn_to_memslot() itself in a header, which would
lead to increased code size, this puts __gfn_to_memslot() in a header.
Then, the non-modular uses of gfn_to_memslot() are changed to call
__gfn_to_memslot() instead.  This way there is only one place in the
source code that needs to be changed should the gfn_to_memslot()
implementation need to be modified.

On powerpc, the Book3S HV style of KVM has code that is called from
real mode which needs to call gfn_to_memslot() and thus needs this.
(Module code is allocated in the vmalloc region, which can't be
accessed in real mode.)

With this, we can remove builtin_gfn_to_memslot() from book3s_hv_rm_mmu.c.

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
v3: Add comment, change kvm_gfn_to_hva_cache_init as requested.

 arch/powerpc/kvm/book3s_hv_rm_mmu.c |   23 ++---------------------
 include/linux/kvm_host.h            |   25 +++++++++++++++++++++++++
 virt/kvm/kvm_main.c                 |   21 +--------------------
 3 files changed, 28 insertions(+), 41 deletions(-)
Alexander Graf - Jan. 16, 2012, 1:18 p.m.
On 13.01.2012, at 07:09, Paul Mackerras wrote:

> This moves __gfn_to_memslot() and search_memslots() from kvm_main.c to
> kvm_host.h to reduce the code duplication caused by the need for
> non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c to call
> gfn_to_memslot() in real mode.
> 
> Rather than putting gfn_to_memslot() itself in a header, which would
> lead to increased code size, this puts __gfn_to_memslot() in a header.
> Then, the non-modular uses of gfn_to_memslot() are changed to call
> __gfn_to_memslot() instead.  This way there is only one place in the
> source code that needs to be changed should the gfn_to_memslot()
> implementation need to be modified.
> 
> On powerpc, the Book3S HV style of KVM has code that is called from
> real mode which needs to call gfn_to_memslot() and thus needs this.
> (Module code is allocated in the vmalloc region, which can't be
> accessed in real mode.)
> 
> With this, we can remove builtin_gfn_to_memslot() from book3s_hv_rm_mmu.c.
> 
> Signed-off-by: Paul Mackerras <paulus@samba.org>

Avi?


Alex

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Avi Kivity - Jan. 16, 2012, 1:21 p.m.
On 01/16/2012 03:18 PM, Alexander Graf wrote:
> Avi?

ACK!
Alexander Graf - Jan. 16, 2012, 1:30 p.m.
On 13.01.2012, at 07:09, Paul Mackerras wrote:

> This moves __gfn_to_memslot() and search_memslots() from kvm_main.c to
> kvm_host.h to reduce the code duplication caused by the need for
> non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c to call
> gfn_to_memslot() in real mode.
> 
> Rather than putting gfn_to_memslot() itself in a header, which would
> lead to increased code size, this puts __gfn_to_memslot() in a header.
> Then, the non-modular uses of gfn_to_memslot() are changed to call
> __gfn_to_memslot() instead.  This way there is only one place in the
> source code that needs to be changed should the gfn_to_memslot()
> implementation need to be modified.
> 
> On powerpc, the Book3S HV style of KVM has code that is called from
> real mode which needs to call gfn_to_memslot() and thus needs this.
> (Module code is allocated in the vmalloc region, which can't be
> accessed in real mode.)
> 
> With this, we can remove builtin_gfn_to_memslot() from book3s_hv_rm_mmu.c.

Which tree is this against? I got this diff between your patch and the patch when applied on my tree:

-@@ -97,7 +78,7 @@ static void remove_revmap_chain(struct kvm *kvm, long pte_index,
- 	rev = real_vmalloc_addr(&kvm->arch.revmap[pte_index]);
- 	ptel = rev->guest_rpte;
+@@ -99,7 +80,7 @@ static void remove_revmap_chain(struct kvm *kvm, long pte_index,
+ 	rcbits = hpte_r & (HPTE_R_R | HPTE_R_C);
+ 	ptel = rev->guest_rpte |= rcbits;

Since this is completely unrelated to the actual change, I'll apply the patch either way. It'd just be interesting to know.


Alex

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Paul Mackerras - Jan. 17, 2012, 5:02 a.m.
On Mon, Jan 16, 2012 at 02:30:41PM +0100, Alexander Graf wrote:

> Which tree is this against? I got this diff between your patch and the patch when applied on my tree:

It's against your tree (previously) plus my first 13-patch series, but
not the second series of 5 patches, which presumably why you got the
difference.  Sounds like you got it applied OK; if not let me know and
I'll rebase against your current tree.

Paul.
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Patch

diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index d3e36fc..9055cd2 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -21,25 +21,6 @@ 
 #include <asm/synch.h>
 #include <asm/ppc-opcode.h>
 
-/*
- * Since this file is built in even if KVM is a module, we need
- * a local copy of this function for the case where kvm_main.c is
- * modular.
- */
-static struct kvm_memory_slot *builtin_gfn_to_memslot(struct kvm *kvm,
-						gfn_t gfn)
-{
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
-
-	slots = kvm_memslots(kvm);
-	kvm_for_each_memslot(memslot, slots)
-		if (gfn >= memslot->base_gfn &&
-		      gfn < memslot->base_gfn + memslot->npages)
-			return memslot;
-	return NULL;
-}
-
 /* Translate address of a vmalloc'd thing to a linear map address */
 static void *real_vmalloc_addr(void *x)
 {
@@ -97,7 +78,7 @@  static void remove_revmap_chain(struct kvm *kvm, long pte_index,
 	rev = real_vmalloc_addr(&kvm->arch.revmap[pte_index]);
 	ptel = rev->guest_rpte;
 	gfn = hpte_rpn(ptel, hpte_page_size(hpte_v, ptel));
-	memslot = builtin_gfn_to_memslot(kvm, gfn);
+	memslot = __gfn_to_memslot(kvm_memslots(kvm), gfn);
 	if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
 		return;
 
@@ -171,7 +152,7 @@  long kvmppc_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
 	/* Find the memslot (if any) for this address */
 	gpa = (ptel & HPTE_R_RPN) & ~(psize - 1);
 	gfn = gpa >> PAGE_SHIFT;
-	memslot = builtin_gfn_to_memslot(kvm, gfn);
+	memslot = __gfn_to_memslot(kvm_memslots(kvm), gfn);
 	pa = 0;
 	is_io = ~0ul;
 	rmap = NULL;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ec79a45..688f37b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -649,6 +649,31 @@  static inline void kvm_guest_exit(void)
 	current->flags &= ~PF_VCPU;
 }
 
+/*
+ * search_memslots() and __gfn_to_memslot() are here because they are
+ * used in non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c.
+ * gfn_to_memslot() itself isn't here as an inline because that would
+ * bloat other code too much.
+ */
+static inline struct kvm_memory_slot *
+search_memslots(struct kvm_memslots *slots, gfn_t gfn)
+{
+	struct kvm_memory_slot *memslot;
+
+	kvm_for_each_memslot(memslot, slots)
+		if (gfn >= memslot->base_gfn &&
+		      gfn < memslot->base_gfn + memslot->npages)
+			return memslot;
+
+	return NULL;
+}
+
+static inline struct kvm_memory_slot *
+__gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
+{
+	return search_memslots(slots, gfn);
+}
+
 static inline int memslot_id(struct kvm *kvm, gfn_t gfn)
 {
 	return gfn_to_memslot(kvm, gfn)->id;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c144132..8ae6b76 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -640,19 +640,6 @@  static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
 }
 #endif /* !CONFIG_S390 */
 
-static struct kvm_memory_slot *
-search_memslots(struct kvm_memslots *slots, gfn_t gfn)
-{
-	struct kvm_memory_slot *memslot;
-
-	kvm_for_each_memslot(memslot, slots)
-		if (gfn >= memslot->base_gfn &&
-		      gfn < memslot->base_gfn + memslot->npages)
-			return memslot;
-
-	return NULL;
-}
-
 static int cmp_memslot(const void *slot1, const void *slot2)
 {
 	struct kvm_memory_slot *s1, *s2;
@@ -1031,12 +1018,6 @@  int kvm_is_error_hva(unsigned long addr)
 }
 EXPORT_SYMBOL_GPL(kvm_is_error_hva);
 
-static struct kvm_memory_slot *__gfn_to_memslot(struct kvm_memslots *slots,
-						gfn_t gfn)
-{
-	return search_memslots(slots, gfn);
-}
-
 struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn)
 {
 	return __gfn_to_memslot(kvm_memslots(kvm), gfn);
@@ -1459,7 +1440,7 @@  int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 
 	ghc->gpa = gpa;
 	ghc->generation = slots->generation;
-	ghc->memslot = __gfn_to_memslot(slots, gfn);
+	ghc->memslot = gfn_to_memslot(kvm, gfn);
 	ghc->hva = gfn_to_hva_many(ghc->memslot, gfn, NULL);
 	if (!kvm_is_error_hva(ghc->hva))
 		ghc->hva += offset;