[PATCH 02/10] xen/p2m: change p2m_missing_* to p2m_identity_*

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

From: Konrad Rzeszutek Wilk <konrad@kernel.org>

We are going to alter how we think about P2M. Most of the
P2M contains MFN, and areas that are not populated are
considered to be "missing". Missing means that the PFN
is either not set for this guest (not have that much memory
allocated) or is under the balloon driver ownership.

We are instead now going to think of those not populated
areas as "identity." Meaning that that the PFN for which
we would get the p2m_identity we will provide the the PFN
value back instead of P2M_MISSING. Essentially treating
those regions as PFN==MFN.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/x86/xen/mmu.c |   59 ++++++++++++++++++++++++++-------------------------
 1 files changed, 30 insertions(+), 29 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 44924e5..d6d0276 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -209,9 +209,9 @@ unsigned long xen_max_p2m_pfn __read_mostly;
 #define MAX_P2M_PFN		(P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
 
 /* Placeholders for holes in the address space */
-static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
-static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
-static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
+static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
+static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_identity, P2M_MID_PER_PAGE);
+static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_identity_mfn, P2M_MID_PER_PAGE);
 
 static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
 static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
@@ -241,7 +241,7 @@ static void p2m_top_init(unsigned long ***top)
 	unsigned i;
 
 	for (i = 0; i < P2M_TOP_PER_PAGE; i++)
-		top[i] = p2m_mid_missing;
+		top[i] = p2m_mid_identity;
 }
 
 static void p2m_top_mfn_init(unsigned long *top)
@@ -249,7 +249,7 @@ static void p2m_top_mfn_init(unsigned long *top)
 	unsigned i;
 
 	for (i = 0; i < P2M_TOP_PER_PAGE; i++)
-		top[i] = virt_to_mfn(p2m_mid_missing_mfn);
+		top[i] = virt_to_mfn(p2m_mid_identity_mfn);
 }
 
 static void p2m_top_mfn_p_init(unsigned long **top)
@@ -257,7 +257,7 @@ static void p2m_top_mfn_p_init(unsigned long **top)
 	unsigned i;
 
 	for (i = 0; i < P2M_TOP_PER_PAGE; i++)
-		top[i] = p2m_mid_missing_mfn;
+		top[i] = p2m_mid_identity_mfn;
 }
 
 static void p2m_mid_init(unsigned long **mid)
@@ -265,7 +265,7 @@ static void p2m_mid_init(unsigned long **mid)
 	unsigned i;
 
 	for (i = 0; i < P2M_MID_PER_PAGE; i++)
-		mid[i] = p2m_missing;
+		mid[i] = p2m_identity;
 }
 
 static void p2m_mid_mfn_init(unsigned long *mid)
@@ -273,7 +273,7 @@ static void p2m_mid_mfn_init(unsigned long *mid)
 	unsigned i;
 
 	for (i = 0; i < P2M_MID_PER_PAGE; i++)
-		mid[i] = virt_to_mfn(p2m_missing);
+		mid[i] = virt_to_mfn(p2m_identity);
 }
 
 static void p2m_init(unsigned long *p2m)
@@ -300,8 +300,8 @@ void xen_build_mfn_list_list(void)
 
 	/* Pre-initialize p2m_top_mfn to be completely missing */
 	if (p2m_top_mfn == NULL) {
-		p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
-		p2m_mid_mfn_init(p2m_mid_missing_mfn);
+		p2m_mid_identity_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
+		p2m_mid_mfn_init(p2m_mid_identity_mfn);
 
 		p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
 		p2m_top_mfn_p_init(p2m_top_mfn_p);
@@ -310,7 +310,7 @@ void xen_build_mfn_list_list(void)
 		p2m_top_mfn_init(p2m_top_mfn);
 	} else {
 		/* Reinitialise, mfn's all change after migration */
-		p2m_mid_mfn_init(p2m_mid_missing_mfn);
+		p2m_mid_mfn_init(p2m_mid_identity_mfn);
 	}
 
 	for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
@@ -326,15 +326,15 @@ void xen_build_mfn_list_list(void)
 		 * they're just missing, just update the stored mfn,
 		 * since all could have changed over a migrate.
 		 */
-		if (mid == p2m_mid_missing) {
+		if (mid == p2m_mid_identity) {
 			BUG_ON(mididx);
-			BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
-			p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
+			BUG_ON(mid_mfn_p != p2m_mid_identity_mfn);
+			p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_identity_mfn);
 			pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
 			continue;
 		}
 
-		if (mid_mfn_p == p2m_mid_missing_mfn) {
+		if (mid_mfn_p == p2m_mid_identity_mfn) {
 			/*
 			 * XXX boot-time only!  We should never find
 			 * missing parts of the mfn tree after
@@ -370,11 +370,11 @@ void __init xen_build_dynamic_phys_to_machine(void)
 
 	xen_max_p2m_pfn = max_pfn;
 
-	p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
-	p2m_init(p2m_missing);
+	p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
+	p2m_init(p2m_identity);
 
-	p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
-	p2m_mid_init(p2m_mid_missing);
+	p2m_mid_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
+	p2m_mid_init(p2m_mid_identity);
 
 	p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
 	p2m_top_init(p2m_top);
@@ -388,7 +388,7 @@ void __init xen_build_dynamic_phys_to_machine(void)
 		unsigned topidx = p2m_top_index(pfn);
 		unsigned mididx = p2m_mid_index(pfn);
 
-		if (p2m_top[topidx] == p2m_mid_missing) {
+		if (p2m_top[topidx] == p2m_mid_identity) {
 			unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
 			p2m_mid_init(mid);
 
@@ -443,7 +443,7 @@ static bool alloc_p2m(unsigned long pfn)
 	top_p = &p2m_top[topidx];
 	mid = *top_p;
 
-	if (mid == p2m_mid_missing) {
+	if (mid == p2m_mid_identity) {
 		/* Mid level is missing, allocate a new one */
 		mid = alloc_p2m_page();
 		if (!mid)
@@ -451,7 +451,7 @@ static bool alloc_p2m(unsigned long pfn)
 
 		p2m_mid_init(mid);
 
-		if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
+		if (cmpxchg(top_p, p2m_mid_identity, mid) != p2m_mid_identity)
 			free_p2m_page(mid);
 	}
 
@@ -460,9 +460,9 @@ static bool alloc_p2m(unsigned long pfn)
 
 	BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
 
-	if (mid_mfn == p2m_mid_missing_mfn) {
+	if (mid_mfn == p2m_mid_identity_mfn) {
 		/* Separately check the mid mfn level */
-		unsigned long missing_mfn;
+		unsigned long identity_mfn;
 		unsigned long mid_mfn_mfn;
 
 		mid_mfn = alloc_p2m_page();
@@ -471,15 +471,16 @@ static bool alloc_p2m(unsigned long pfn)
 
 		p2m_mid_mfn_init(mid_mfn);
 
-		missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
+		identity_mfn = virt_to_mfn(p2m_mid_identity_mfn);
 		mid_mfn_mfn = virt_to_mfn(mid_mfn);
-		if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
+		if (cmpxchg(top_mfn_p, identity_mfn, mid_mfn_mfn) !=
+		    identity_mfn)
 			free_p2m_page(mid_mfn);
 		else
 			p2m_top_mfn_p[topidx] = mid_mfn;
 	}
 
-	if (p2m_top[topidx][mididx] == p2m_missing) {
+	if (p2m_top[topidx][mididx] == p2m_identity) {
 		/* p2m leaf page is missing */
 		unsigned long *p2m;
 
@@ -489,7 +490,7 @@ static bool alloc_p2m(unsigned long pfn)
 
 		p2m_init(p2m);
 
-		if (cmpxchg(&mid[mididx], p2m_missing, p2m) != p2m_missing)
+		if (cmpxchg(&mid[mididx], p2m_identity, p2m) != p2m_identity)
 			free_p2m_page(p2m);
 		else
 			mid_mfn[mididx] = virt_to_mfn(p2m);
@@ -512,7 +513,7 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 	mididx = p2m_mid_index(pfn);
 	idx = p2m_index(pfn);
 
-	if (p2m_top[topidx][mididx] == p2m_missing)
+	if (p2m_top[topidx][mididx] == p2m_identity)
 		return mfn == INVALID_P2M_ENTRY;
 
 	p2m_top[topidx][mididx][idx] = mfn;
-- 
1.7.1