[PATCH 0/6 v5] kvm: powerpc: use cache attributes from linux pte

From: Bharat Bhushan <redacted>

First patch is a typo fix where book3e define _PAGE_LENDIAN while it
should be defined as _PAGE_ENDIAN. This seems to show that this is never exercised :-)

Second and third patch is to allow guest controlling "G"-Guarded and "E"-Endian TLB attributes respectively.

Fourth patch is moving functions/logic in common code so they can be used on booke also.

Fifth and Sixth patch is actually setting caching attributes (TLB.WIMGE) using corresponding Linux pte.

v3->v5
 - Fix tlb-reference-flag clearing issue (patch 4/6)
 - There was a patch (4/6 powerpc: move linux pte/hugepte search to more generic file)
   in the last series of this patchset which was moving pte/hugepte search functions to
   generic file. That patch is no more needed as some other patch is already applied to fix that :)

v2->v3
 - now lookup_linux_pte() only have pte search logic and it does not
   set any access flags in pte. There is already a function for setting
   access flag which will be called explicitly where needed.
   On booke we only need to search for pte to get WIMG.

v1->v2
 - Earlier caching attributes (WIMGE) were set based of page is RAM or not
   But now we get these attributes from corresponding Linux PTE.

Bharat Bhushan (6):
  powerpc: book3e: _PAGE_LENDIAN must be _PAGE_ENDIAN
  kvm: powerpc: allow guest control "E" attribute in mas2
  kvm: powerpc: allow guest control "G" attribute in mas2
  kvm: powerpc: keep only pte search logic in lookup_linux_pte
  kvm: booke: clear host tlb reference flag on guest tlb invalidation
  kvm: powerpc: use caching attributes as per linux pte

 arch/powerpc/include/asm/kvm_host.h   |    2 +-
 arch/powerpc/include/asm/pgtable.h    |   24 ++++++++++++++++
 arch/powerpc/include/asm/pte-book3e.h |    2 +-
 arch/powerpc/kvm/book3s_hv_rm_mmu.c   |   36 ++++++++----------------
 arch/powerpc/kvm/booke.c              |    2 +-
 arch/powerpc/kvm/e500.h               |   10 ++++--
 arch/powerpc/kvm/e500_mmu_host.c      |   50 +++++++++++++++++++--------------
 7 files changed, 74 insertions(+), 52 deletions(-)

For booke3e _PAGE_ENDIAN is not defined. Infact what is defined
is "_PAGE_LENDIAN" which is wrong and that should be _PAGE_ENDIAN.
There are no compilation errors as
arch/powerpc/include/asm/pte-common.h defines _PAGE_ENDIAN to 0
as it is not defined anywhere.

Signed-off-by: Bharat Bhushan <redacted>
---
v1->v5
 - no change

 arch/powerpc/include/asm/pte-book3e.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/pte-book3e.h b/arch/powerpc/include/asm/pte-book3e.h
index 0156702..576ad88 100644
--- a/arch/powerpc/include/asm/pte-book3e.h
+++ b/arch/powerpc/include/asm/pte-book3e.h

@@ -40,7 +40,7 @@
 #define _PAGE_U1	0x010000
 #define _PAGE_U0	0x020000
 #define _PAGE_ACCESSED	0x040000
-#define _PAGE_LENDIAN	0x080000
+#define _PAGE_ENDIAN	0x080000
 #define _PAGE_GUARDED	0x100000
 #define _PAGE_COHERENT	0x200000 /* M: enforce memory coherence */
 #define _PAGE_NO_CACHE	0x400000 /* I: cache inhibit */

-- 
1.7.0.4

"E" bit in MAS2 bit indicates whether the page is accessed
in Little-Endian or Big-Endian byte order.
There is no reason to stop guest setting  "E", so allow him."

Signed-off-by: Bharat Bhushan <redacted>
---
v1->v5
 - no change
 arch/powerpc/kvm/e500.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/kvm/e500.h b/arch/powerpc/kvm/e500.h
index c2e5e98..277cb18 100644
--- a/arch/powerpc/kvm/e500.h
+++ b/arch/powerpc/kvm/e500.h

@@ -117,7 +117,7 @@ static inline struct kvmppc_vcpu_e500 *to_e500(struct kvm_vcpu *vcpu)
 #define E500_TLB_USER_PERM_MASK (MAS3_UX|MAS3_UR|MAS3_UW)
 #define E500_TLB_SUPER_PERM_MASK (MAS3_SX|MAS3_SR|MAS3_SW)
 #define MAS2_ATTRIB_MASK \
-	  (MAS2_X0 | MAS2_X1)
+	  (MAS2_X0 | MAS2_X1 | MAS2_E)
 #define MAS3_ATTRIB_MASK \
 	  (MAS3_U0 | MAS3_U1 | MAS3_U2 | MAS3_U3 \
 	   | E500_TLB_USER_PERM_MASK | E500_TLB_SUPER_PERM_MASK)

-- 
1.7.0.4

"G" bit in MAS2 indicates whether the page is Guarded.
There is no reason to stop guest setting  "G", so allow him.

Signed-off-by: Bharat Bhushan <redacted>
---
v1->v5
 - no change
 arch/powerpc/kvm/e500.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/kvm/e500.h b/arch/powerpc/kvm/e500.h
index 277cb18..4fd9650 100644
--- a/arch/powerpc/kvm/e500.h
+++ b/arch/powerpc/kvm/e500.h

@@ -117,7 +117,7 @@ static inline struct kvmppc_vcpu_e500 *to_e500(struct kvm_vcpu *vcpu)
 #define E500_TLB_USER_PERM_MASK (MAS3_UX|MAS3_UR|MAS3_UW)
 #define E500_TLB_SUPER_PERM_MASK (MAS3_SX|MAS3_SR|MAS3_SW)
 #define MAS2_ATTRIB_MASK \
-	  (MAS2_X0 | MAS2_X1 | MAS2_E)
+	  (MAS2_X0 | MAS2_X1 | MAS2_E | MAS2_G)
 #define MAS3_ATTRIB_MASK \
 	  (MAS3_U0 | MAS3_U1 | MAS3_U2 | MAS3_U3 \
 	   | E500_TLB_USER_PERM_MASK | E500_TLB_SUPER_PERM_MASK)

-- 
1.7.0.4

lookup_linux_pte() was searching for a pte and also sets access
flags is writable. This function now searches only pte while
access flag setting is done explicitly.

This pte lookup is not kvm specific, so moved to common code (asm/pgtable.h)
My Followup patch will use this on booke.

Signed-off-by: Bharat Bhushan <redacted>
---
v4->v5
 - No change

 arch/powerpc/include/asm/pgtable.h  |   24 +++++++++++++++++++++++
 arch/powerpc/kvm/book3s_hv_rm_mmu.c |   36 +++++++++++-----------------------
 2 files changed, 36 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index 7d6eacf..3a5de5c 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h

@@ -223,6 +223,30 @@ extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 #endif
 pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
 				 unsigned *shift);
+
+static inline pte_t *lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
+				     unsigned long *pte_sizep)
+{
+	pte_t *ptep;
+	unsigned long ps = *pte_sizep;
+	unsigned int shift;
+
+	ptep = find_linux_pte_or_hugepte(pgdir, hva, &shift);
+	if (!ptep)
+		return __pte(0);
+	if (shift)
+		*pte_sizep = 1ul << shift;
+	else
+		*pte_sizep = PAGE_SIZE;
+
+	if (ps > *pte_sizep)
+		return __pte(0);
+
+	if (!pte_present(*ptep))
+		return __pte(0);
+
+	return ptep;
+}
 #endif /* __ASSEMBLY__ */
 
 #endif /* __KERNEL__ */

diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 45e30d6..74fa7f8 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c

@@ -134,25 +134,6 @@ static void remove_revmap_chain(struct kvm *kvm, long pte_index,
 	unlock_rmap(rmap);
 }
 
-static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
-			      int writing, unsigned long *pte_sizep)
-{
-	pte_t *ptep;
-	unsigned long ps = *pte_sizep;
-	unsigned int hugepage_shift;
-
-	ptep = find_linux_pte_or_hugepte(pgdir, hva, &hugepage_shift);
-	if (!ptep)
-		return __pte(0);
-	if (hugepage_shift)
-		*pte_sizep = 1ul << hugepage_shift;
-	else
-		*pte_sizep = PAGE_SIZE;
-	if (ps > *pte_sizep)
-		return __pte(0);
-	return kvmppc_read_update_linux_pte(ptep, writing, hugepage_shift);
-}
-
 static inline void unlock_hpte(unsigned long *hpte, unsigned long hpte_v)
 {
 	asm volatile(PPC_RELEASE_BARRIER "" : : : "memory");

@@ -173,6 +154,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
 	unsigned long is_io;
 	unsigned long *rmap;
 	pte_t pte;
+	pte_t *ptep;
 	unsigned int writing;
 	unsigned long mmu_seq;
 	unsigned long rcbits;

@@ -231,8 +213,9 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
 
 		/* Look up the Linux PTE for the backing page */
 		pte_size = psize;
-		pte = lookup_linux_pte(pgdir, hva, writing, &pte_size);
-		if (pte_present(pte)) {
+		ptep = lookup_linux_pte(pgdir, hva, &pte_size);
+		if (pte_present(pte_val(*ptep))) {
+			pte = kvmppc_read_update_linux_pte(ptep, writing);
 			if (writing && !pte_write(pte))
 				/* make the actual HPTE be read-only */
 				ptel = hpte_make_readonly(ptel);

@@ -661,15 +644,20 @@ long kvmppc_h_protect(struct kvm_vcpu *vcpu, unsigned long flags,
 			struct kvm_memory_slot *memslot;
 			pgd_t *pgdir = vcpu->arch.pgdir;
 			pte_t pte;
+			pte_t *ptep;
 
 			psize = hpte_page_size(v, r);
 			gfn = ((r & HPTE_R_RPN) & ~(psize - 1)) >> PAGE_SHIFT;
 			memslot = __gfn_to_memslot(kvm_memslots(kvm), gfn);
 			if (memslot) {
 				hva = __gfn_to_hva_memslot(memslot, gfn);
-				pte = lookup_linux_pte(pgdir, hva, 1, &psize);
-				if (pte_present(pte) && !pte_write(pte))
-					r = hpte_make_readonly(r);
+				ptep = lookup_linux_pte(pgdir, hva, &psize);
+				if (pte_present(pte_val(*ptep))) {
+					pte = kvmppc_read_update_linux_pte(ptep,
+									   1);
+					if (pte_present(pte) && !pte_write(pte))
+						r = hpte_make_readonly(r);
+				}
 			}
 		}
 	}

-- 
1.7.0.4

On booke, "struct tlbe_ref" contains host tlb mapping information
(pfn: for guest-pfn to pfn, flags: attribute associated with this mapping)
for a guest tlb entry. So when a guest creates a TLB entry then
"struct tlbe_ref" is set to point to valid "pfn" and set attributes in
"flags" field of the above said structure. When a guest TLB entry is
invalidated then flags field of corresponding "struct tlbe_ref" is
updated to point that this is no more valid, also we selectively clear
some other attribute bits, example: if E500_TLB_BITMAP was set then we clear
E500_TLB_BITMAP, if E500_TLB_TLB0 is set then we clear this.

Ideally we should clear complete "flags" as this entry is invalid and does not
have anything to re-used. The other part of the problem is that when we use
the same entry again then also we do not clear (started doing or-ing etc).

So far it was working because the selectively clearing mentioned above
actually clears "flags" what was set during TLB mapping. But the problem
starts coming when we add more attributes to this then we need to selectively
clear them and which is not needed.

This patch we do both
        - Clear "flags" when invalidating;
        - Clear "flags" when reusing same entry later

Signed-off-by: Bharat Bhushan <redacted>
---
v3-> v5
 - New patch (found this issue when doing vfio-pci development)

 arch/powerpc/kvm/e500_mmu_host.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 1c6a9d7..60f5a3c 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c

@@ -217,7 +217,8 @@ void inval_gtlbe_on_host(struct kvmppc_vcpu_e500 *vcpu_e500, int tlbsel,
 		}
 		mb();
 		vcpu_e500->g2h_tlb1_map[esel] = 0;
-		ref->flags &= ~(E500_TLB_BITMAP | E500_TLB_VALID);
+		/* Clear flags as TLB is not backed by the host anymore */
+		ref->flags = 0;
 		local_irq_restore(flags);
 	}
 

@@ -227,7 +228,8 @@ void inval_gtlbe_on_host(struct kvmppc_vcpu_e500 *vcpu_e500, int tlbsel,
 		 * rarely and is not worth optimizing. Invalidate everything.
 		 */
 		kvmppc_e500_tlbil_all(vcpu_e500);
-		ref->flags &= ~(E500_TLB_TLB0 | E500_TLB_VALID);
+		/* Clear flags as TLB is not backed by the host anymore */
+		ref->flags = 0;
 	}
 
 	/* Already invalidated in between */

@@ -237,8 +239,8 @@ void inval_gtlbe_on_host(struct kvmppc_vcpu_e500 *vcpu_e500, int tlbsel,
 	/* Guest tlbe is backed by at most one host tlbe per shadow pid. */
 	kvmppc_e500_tlbil_one(vcpu_e500, gtlbe);
 
-	/* Mark the TLB as not backed by the host anymore */
-	ref->flags &= ~E500_TLB_VALID;
+	/* Clear flags as TLB is not backed by the host anymore */
+	ref->flags = 0;
 }
 
 static inline int tlbe_is_writable(struct kvm_book3e_206_tlb_entry *tlbe)

@@ -251,7 +253,7 @@ static inline void kvmppc_e500_ref_setup(struct tlbe_ref *ref,
 					 pfn_t pfn)
 {
 	ref->pfn = pfn;
-	ref->flags |= E500_TLB_VALID;
+	ref->flags = E500_TLB_VALID;
 
 	if (tlbe_is_writable(gtlbe))
 		kvm_set_pfn_dirty(pfn);

-- 
1.7.0.4

KVM uses same WIM tlb attributes as the corresponding qemu pte.
For this we now search the linux pte for the requested page and
get these cache caching/coherency attributes from pte.

Signed-off-by: Bharat Bhushan <redacted>
---
v4->v5
 - No change

 arch/powerpc/include/asm/kvm_host.h |    2 +-
 arch/powerpc/kvm/booke.c            |    2 +-
 arch/powerpc/kvm/e500.h             |    8 ++++--
 arch/powerpc/kvm/e500_mmu_host.c    |   38 ++++++++++++++++++++--------------
 4 files changed, 29 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 9741bf0..775f0e8 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h

@@ -538,6 +538,7 @@ struct kvm_vcpu_arch {
 #endif
 	gpa_t paddr_accessed;
 	gva_t vaddr_accessed;
+	pgd_t *pgdir;
 
 	u8 io_gpr; /* GPR used as IO source/target */
 	u8 mmio_is_bigendian;

@@ -595,7 +596,6 @@ struct kvm_vcpu_arch {
 	struct list_head run_list;
 	struct task_struct *run_task;
 	struct kvm_run *kvm_run;
-	pgd_t *pgdir;
 
 	spinlock_t vpa_update_lock;
 	struct kvmppc_vpa vpa;

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 17722d8..4171c7d 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c

@@ -695,7 +695,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 
 	kvmppc_load_guest_fp(vcpu);
 #endif
-
+	vcpu->arch.pgdir = current->mm->pgd;
 	kvmppc_fix_ee_before_entry();
 
 	ret = __kvmppc_vcpu_run(kvm_run, vcpu);

diff --git a/arch/powerpc/kvm/e500.h b/arch/powerpc/kvm/e500.h
index 4fd9650..a326178 100644
--- a/arch/powerpc/kvm/e500.h
+++ b/arch/powerpc/kvm/e500.h

@@ -31,11 +31,13 @@ enum vcpu_ftr {
 #define E500_TLB_NUM   2
 
 /* entry is mapped somewhere in host TLB */
-#define E500_TLB_VALID		(1 << 0)
+#define E500_TLB_VALID		(1 << 31)
 /* TLB1 entry is mapped by host TLB1, tracked by bitmaps */
-#define E500_TLB_BITMAP		(1 << 1)
+#define E500_TLB_BITMAP		(1 << 30)
 /* TLB1 entry is mapped by host TLB0 */
-#define E500_TLB_TLB0		(1 << 2)
+#define E500_TLB_TLB0		(1 << 29)
+/* bits [6-5] MAS2_X1 and MAS2_X0 and [4-0] bits for WIMGE */
+#define E500_TLB_MAS2_ATTR	(0x7f)
 
 struct tlbe_ref {
 	pfn_t pfn;		/* valid only for TLB0, except briefly */

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 60f5a3c..654c368 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c

@@ -64,15 +64,6 @@ static inline u32 e500_shadow_mas3_attrib(u32 mas3, int usermode)
 	return mas3;
 }
 
-static inline u32 e500_shadow_mas2_attrib(u32 mas2, int usermode)
-{
-#ifdef CONFIG_SMP
-	return (mas2 & MAS2_ATTRIB_MASK) | MAS2_M;
-#else
-	return mas2 & MAS2_ATTRIB_MASK;
-#endif
-}
-
 /*
  * writing shadow tlb entry to host TLB
  */

@@ -250,10 +241,12 @@ static inline int tlbe_is_writable(struct kvm_book3e_206_tlb_entry *tlbe)
 
 static inline void kvmppc_e500_ref_setup(struct tlbe_ref *ref,
 					 struct kvm_book3e_206_tlb_entry *gtlbe,
-					 pfn_t pfn)
+					 pfn_t pfn, unsigned int wimg)
 {
 	ref->pfn = pfn;
 	ref->flags = E500_TLB_VALID;
+	/* Use guest supplied MAS2_G and MAS2_E */
+	ref->flags |= (gtlbe->mas2 & MAS2_ATTRIB_MASK) | wimg;
 
 	if (tlbe_is_writable(gtlbe))
 		kvm_set_pfn_dirty(pfn);

@@ -314,8 +307,7 @@ static void kvmppc_e500_setup_stlbe(
 
 	/* Force IPROT=0 for all guest mappings. */
 	stlbe->mas1 = MAS1_TSIZE(tsize) | get_tlb_sts(gtlbe) | MAS1_VALID;
-	stlbe->mas2 = (gvaddr & MAS2_EPN) |
-		      e500_shadow_mas2_attrib(gtlbe->mas2, pr);
+	stlbe->mas2 = (gvaddr & MAS2_EPN) | (ref->flags & E500_TLB_MAS2_ATTR);
 	stlbe->mas7_3 = ((u64)pfn << PAGE_SHIFT) |
 			e500_shadow_mas3_attrib(gtlbe->mas7_3, pr);
 

@@ -334,6 +326,10 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 	unsigned long hva;
 	int pfnmap = 0;
 	int tsize = BOOK3E_PAGESZ_4K;
+	unsigned long tsize_pages = 0;
+	pte_t *ptep;
+	unsigned int wimg = 0;
+	pgd_t *pgdir;
 
 	/*
 	 * Translate guest physical to true physical, acquiring

@@ -396,7 +392,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 			 */
 
 			for (; tsize > BOOK3E_PAGESZ_4K; tsize -= 2) {
-				unsigned long gfn_start, gfn_end, tsize_pages;
+				unsigned long gfn_start, gfn_end;
 				tsize_pages = 1 << (tsize - 2);
 
 				gfn_start = gfn & ~(tsize_pages - 1);

@@ -438,9 +434,10 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 	}
 
 	if (likely(!pfnmap)) {
-		unsigned long tsize_pages = 1 << (tsize + 10 - PAGE_SHIFT);
+		tsize_pages = 1 << (tsize + 10 - PAGE_SHIFT);
+
 		pfn = gfn_to_pfn_memslot(slot, gfn);
-		if (is_error_noslot_pfn(pfn)) {
+		if (is_error_noslot_pfn(pfn) && printk_ratelimit()) {
 			printk(KERN_ERR "Couldn't get real page for gfn %lx!\n",
 					(long)gfn);
 			return -EINVAL;

@@ -451,7 +448,16 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 		gvaddr &= ~((tsize_pages << PAGE_SHIFT) - 1);
 	}
 
-	kvmppc_e500_ref_setup(ref, gtlbe, pfn);
+	pgdir = vcpu_e500->vcpu.arch.pgdir;
+	ptep = lookup_linux_pte(pgdir, hva, &tsize_pages);
+	if (pte_present(*ptep)) {
+		wimg = (pte_val(*ptep) >> PTE_WIMGE_SHIFT) & MAS2_WIMGE_MASK;
+	} else if (printk_ratelimit()) {
+		printk(KERN_ERR "%s: pte not present: gfn %lx, pfn %lx\n",
+				__func__, (long)gfn, pfn);
+		return -EINVAL;
+	}
+	kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg);
 
 	kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
 				ref, gvaddr, stlbe);

-- 
1.7.0.4

On Thu, 2013-09-19 at 11:32 +0530, Bharat Bhushan wrote:

This breaks when you have both E500_TLB_BITMAP and E500_TLB_TLB0 set.

Instead, just convert the final E500_TLB_VALID clearing at the end into
ref->flags = 0, and convert the early return a few lines earlier into
conditional execution of the tlbil_one().

-Scott

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On Thu, 2013-09-19 at 23:19 -0500, Bhushan Bharat-R65777 wrote:

quoted

-----Original Message-----
From: Wood Scott-B07421
Sent: Friday, September 20, 2013 2:38 AM
To: Bhushan Bharat-R65777
Cc: benh@kernel.crashing.org; agraf@suse.de; paulus@samba.org;
kvm@vger.kernel.org; kvm-ppc@vger.kernel.org; linuxppc-dev@lists.ozlabs.org;
Bhushan Bharat-R65777
Subject: Re: [PATCH 5/6 v5] kvm: booke: clear host tlb reference flag on guest
tlb invalidation

This breaks when you have both E500_TLB_BITMAP and E500_TLB_TLB0 set.

I do not see any case where we set both E500_TLB_BITMAP and
E500_TLB_TLB0.

This would happen if you have a guest TLB1 entry that is backed by some
4K pages and some larger pages (e.g. if the guest maps CCSR with one big
TLB1 and there are varying I/O passthrough regions mapped).  It's not
common, but it's possible.

 Also we have not optimized that yet (keeping track of
multiple shadow TLB0 entries for one guest TLB1 entry)

This is about correctness, not optimization.

We uses these bit flags only for TLB1 and if size of stlbe is 4K then
we set E500_TLB_TLB0  otherwise we set E500_TLB_BITMAP. Although I
think that E500_TLB_BITMAP should be set only if stlbe size is less
than gtlbe size.

Why?  Even if there's only one bit set in the map, we need it to keep
track of which entry was used.

-Scott

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On Fri, 2013-09-20 at 13:04 -0500, Bhushan Bharat-R65777 wrote:

quoted

-----Original Message-----
From: Wood Scott-B07421
Sent: Friday, September 20, 2013 9:48 PM
To: Bhushan Bharat-R65777
Cc: Wood Scott-B07421; benh@kernel.crashing.org; agraf@suse.de;
paulus@samba.org; kvm@vger.kernel.org; kvm-ppc@vger.kernel.org; linuxppc-
dev@lists.ozlabs.org
Subject: Re: [PATCH 5/6 v5] kvm: booke: clear host tlb reference flag on guest
tlb invalidation

On Thu, 2013-09-19 at 23:19 -0500, Bhushan Bharat-R65777 wrote:

quoted

We uses these bit flags only for TLB1 and if size of stlbe is 4K then
we set E500_TLB_TLB0  otherwise we set E500_TLB_BITMAP. Although I
think that E500_TLB_BITMAP should be set only if stlbe size is less
than gtlbe size.

Why?  Even if there's only one bit set in the map, we need it to keep track of
which entry was used.

If there is one entry then will not this be simple/faster to not lookup bitmap and guest->host array?
A flag indicate it is 1:1 map and this is physical address.

The difference would be negligible, and you'd have added overhead (both
runtime and complexity) of making this a special case.

-Scott

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DQoNCg==

On 19.09.2013, at 08:02, Bharat Bhushan wrote:

lookup_linux_pte() was searching for a pte and also sets access
flags is writable. This function now searches only pte while
access flag setting is done explicitly.
=20
This pte lookup is not kvm specific, so moved to common code =

(asm/pgtable.h)

My Followup patch will use this on booke.
=20
Signed-off-by: Bharat Bhushan <redacted>
---
v4->v5
- No change
=20
arch/powerpc/include/asm/pgtable.h  |   24 +++++++++++++++++++++++
arch/powerpc/kvm/book3s_hv_rm_mmu.c |   36 =

+++++++++++-----------------------

b/arch/powerpc/include/asm/pgtable.h

sz, unsigned long addr,

#endif
pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
				 unsigned *shift);
+
+static inline pte_t *lookup_linux_pte(pgd_t *pgdir, unsigned long =

hva,

+				     unsigned long *pte_sizep)
+{
+	pte_t *ptep;
+	unsigned long ps =3D *pte_sizep;
+	unsigned int shift;
+
+	ptep =3D find_linux_pte_or_hugepte(pgdir, hva, &shift);
+	if (!ptep)
+		return __pte(0);

This returns a struct pte_t, but your return value of the function is a =
struct pte_t *. So this code will fail compiling with =
STRICT_MM_TYPECHECKS set. Any reason you don't just return NULL here?

That way callers could simply check on if (ptep) ... or you leave the =
return value as struct pte_t.


Alex

+	if (shift)
+		*pte_sizep =3D 1ul << shift;
+	else
+		*pte_sizep =3D PAGE_SIZE;
+
+	if (ps > *pte_sizep)
+		return __pte(0);
+
+	if (!pte_present(*ptep))
+		return __pte(0);

b/arch/powerpc/kvm/book3s_hv_rm_mmu.c

long pte_index,

	unlock_rmap(rmap);
}
=20
-static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
-			      int writing, unsigned long *pte_sizep)
-{
-	pte_t *ptep;
-	unsigned long ps =3D *pte_sizep;
-	unsigned int hugepage_shift;
-
-	ptep =3D find_linux_pte_or_hugepte(pgdir, hva, &hugepage_shift);
-	if (!ptep)
-		return __pte(0);
-	if (hugepage_shift)
-		*pte_sizep =3D 1ul << hugepage_shift;
-	else
-		*pte_sizep =3D PAGE_SIZE;
-	if (ps > *pte_sizep)
-		return __pte(0);
-	return kvmppc_read_update_linux_pte(ptep, writing, =

hugepage_shift);

-}
-
static inline void unlock_hpte(unsigned long *hpte, unsigned long =

hpte_v)

long flags,

long flags,

=20
		/* Look up the Linux PTE for the backing page */
		pte_size =3D psize;
-		pte =3D lookup_linux_pte(pgdir, hva, writing, =

&pte_size);

-		if (pte_present(pte)) {
+		ptep =3D lookup_linux_pte(pgdir, hva, &pte_size);
+		if (pte_present(pte_val(*ptep))) {
+			pte =3D kvmppc_read_update_linux_pte(ptep, =

writing);

unsigned long flags,

			struct kvm_memory_slot *memslot;
			pgd_t *pgdir =3D vcpu->arch.pgdir;
			pte_t pte;
+			pte_t *ptep;
=20
			psize =3D hpte_page_size(v, r);
			gfn =3D ((r & HPTE_R_RPN) & ~(psize - 1)) >> =

PAGE_SHIFT;

			memslot =3D __gfn_to_memslot(kvm_memslots(kvm), =

gfn);

			if (memslot) {
				hva =3D __gfn_to_hva_memslot(memslot, =

gfn);

-				pte =3D lookup_linux_pte(pgdir, hva, 1, =

&psize);

-				if (pte_present(pte) && !pte_write(pte))
-					r =3D hpte_make_readonly(r);
+				ptep =3D lookup_linux_pte(pgdir, hva, =

&psize);

+				if (pte_present(pte_val(*ptep))) {
+					pte =3D =

kvmppc_read_update_linux_pte(ptep,

+									 =

  1);

+					if (pte_present(pte) && =

!pte_write(pte))

+						r =3D =

hpte_make_readonly(r);

+				}
			}
		}
	}
--=20
1.7.0.4
=20
=20
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-----Original Message-----
From: Alexander Graf [mailto:agraf@suse.de]
Sent: Friday, October 04, 2013 6:57 PM
To: Bhushan Bharat-R65777
Cc: benh@kernel.crashing.org; paulus@samba.org; kvm@vger.kernel.org; kvm-
ppc@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; Wood Scott-B07421; Bh=

ushan

Bharat-R65777
Subject: Re: [PATCH 4/6 v5] kvm: powerpc: keep only pte search logic in
lookup_linux_pte
=20
=20
On 19.09.2013, at 08:02, Bharat Bhushan wrote:
=20

quoted

lookup_linux_pte() was searching for a pte and also sets access flags
is writable. This function now searches only pte while access flag
setting is done explicitly.

This pte lookup is not kvm specific, so moved to common code
(asm/pgtable.h) My Followup patch will use this on booke.

Signed-off-by: Bharat Bhushan <redacted>
---
v4->v5
- No change

arch/powerpc/include/asm/pgtable.h  |   24 +++++++++++++++++++++++
arch/powerpc/kvm/book3s_hv_rm_mmu.c |   36 +++++++++++-----------------=

------

quoted

2 files changed, 36 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/include/asm/pgtable.h

b/arch/powerpc/include/asm/pgtable.h
index 7d6eacf..3a5de5c 100644

--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h

@@ -223,6 +223,30 @@ extern int gup_hugepte(pte_t *ptep, unsigned long

sz, unsigned long addr, #endif pte_t *find_linux_pte_or_hugepte(pgd_t
*pgdir, unsigned long ea,
				 unsigned *shift);
+
+static inline pte_t *lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
+				     unsigned long *pte_sizep)
+{
+	pte_t *ptep;
+	unsigned long ps =3D *pte_sizep;
+	unsigned int shift;
+
+	ptep =3D find_linux_pte_or_hugepte(pgdir, hva, &shift);
+	if (!ptep)
+		return __pte(0);

=20
This returns a struct pte_t, but your return value of the function is a s=

truct

pte_t *. So this code will fail compiling with STRICT_MM_TYPECHECKS set. =

Any

reason you don't just return NULL here?

I want to return the ptep (pte pointer) , so yes this should be NULL.
Will correct this.

Thanks
-Bharat

=20
That way callers could simply check on if (ptep) ... or you leave the ret=

urn

value as struct pte_t.
=20
=20
Alex
=20

quoted

+	if (shift)
+		*pte_sizep =3D 1ul << shift;
+	else
+		*pte_sizep =3D PAGE_SIZE;
+
+	if (ps > *pte_sizep)
+		return __pte(0);
+
+	if (!pte_present(*ptep))
+		return __pte(0);

=20

quoted

+
+	return ptep;
+}
#endif /* __ASSEMBLY__ */

#endif /* __KERNEL__ */

diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c

b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 45e30d6..74fa7f8 100644

--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c

@@ -134,25 +134,6 @@ static void remove_revmap_chain(struct kvm *kvm, l=

ong

pte_index,

quoted

	unlock_rmap(rmap);
}

-static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
-			      int writing, unsigned long *pte_sizep)
-{
-	pte_t *ptep;
-	unsigned long ps =3D *pte_sizep;
-	unsigned int hugepage_shift;
-
-	ptep =3D find_linux_pte_or_hugepte(pgdir, hva, &hugepage_shift);
-	if (!ptep)
-		return __pte(0);
-	if (hugepage_shift)
-		*pte_sizep =3D 1ul << hugepage_shift;
-	else
-		*pte_sizep =3D PAGE_SIZE;
-	if (ps > *pte_sizep)
-		return __pte(0);
-	return kvmppc_read_update_linux_pte(ptep, writing, hugepage_shift);
-}
-
static inline void unlock_hpte(unsigned long *hpte, unsigned long
hpte_v) {
	asm volatile(PPC_RELEASE_BARRIER "" : : : "memory"); @@ -173,6 +154,7

@@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,

	unsigned long is_io;
	unsigned long *rmap;
	pte_t pte;
+	pte_t *ptep;
	unsigned int writing;
	unsigned long mmu_seq;
	unsigned long rcbits;

@@ -231,8 +213,9 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned

long flags,

		/* Look up the Linux PTE for the backing page */
		pte_size =3D psize;
-		pte =3D lookup_linux_pte(pgdir, hva, writing, &pte_size);
-		if (pte_present(pte)) {
+		ptep =3D lookup_linux_pte(pgdir, hva, &pte_size);
+		if (pte_present(pte_val(*ptep))) {
+			pte =3D kvmppc_read_update_linux_pte(ptep, writing);
			if (writing && !pte_write(pte))
				/* make the actual HPTE be read-only */
				ptel =3D hpte_make_readonly(ptel);

@@ -661,15 +644,20 @@ long kvmppc_h_protect(struct kvm_vcpu *vcpu, unsi=

gned

long flags,

quoted

			struct kvm_memory_slot *memslot;
			pgd_t *pgdir =3D vcpu->arch.pgdir;
			pte_t pte;
+			pte_t *ptep;

			psize =3D hpte_page_size(v, r);
			gfn =3D ((r & HPTE_R_RPN) & ~(psize - 1)) >> PAGE_SHIFT;
			memslot =3D __gfn_to_memslot(kvm_memslots(kvm), gfn);
			if (memslot) {
				hva =3D __gfn_to_hva_memslot(memslot, gfn);
-				pte =3D lookup_linux_pte(pgdir, hva, 1, &psize);
-				if (pte_present(pte) && !pte_write(pte))
-					r =3D hpte_make_readonly(r);
+				ptep =3D lookup_linux_pte(pgdir, hva, &psize);
+				if (pte_present(pte_val(*ptep))) {
+					pte =3D kvmppc_read_update_linux_pte(ptep,
+									   1);
+					if (pte_present(pte) && !pte_write(pte))
+						r =3D hpte_make_readonly(r);
+				}
			}
		}
	}
--
1.7.0.4


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=20

On 19.09.2013, at 08:02, Bharat Bhushan wrote:

From: Bharat Bhushan <redacted>
=20
First patch is a typo fix where book3e define _PAGE_LENDIAN while it
should be defined as _PAGE_ENDIAN. This seems to show that this is =

never exercised :-)

=20
Second and third patch is to allow guest controlling "G"-Guarded and =

"E"-Endian TLB attributes respectively.

=20
Fourth patch is moving functions/logic in common code so they can be =

used on booke also.

=20
Fifth and Sixth patch is actually setting caching attributes =

(TLB.WIMGE) using corresponding Linux pte.

Thanks, applied 1/6 - 3/6 to kvm-ppc-queue.


Alex

=20
v3->v5
- Fix tlb-reference-flag clearing issue (patch 4/6)
- There was a patch (4/6 powerpc: move linux pte/hugepte search to =

more generic file)

  in the last series of this patchset which was moving pte/hugepte =

search functions to

  generic file. That patch is no more needed as some other patch is =

already applied to fix that :)

=20
v2->v3
- now lookup_linux_pte() only have pte search logic and it does not
  set any access flags in pte. There is already a function for setting
  access flag which will be called explicitly where needed.
  On booke we only need to search for pte to get WIMG.
=20
v1->v2
- Earlier caching attributes (WIMGE) were set based of page is RAM or =

not

  But now we get these attributes from corresponding Linux PTE.
=20
Bharat Bhushan (6):
 powerpc: book3e: _PAGE_LENDIAN must be _PAGE_ENDIAN
 kvm: powerpc: allow guest control "E" attribute in mas2
 kvm: powerpc: allow guest control "G" attribute in mas2
 kvm: powerpc: keep only pte search logic in lookup_linux_pte
 kvm: booke: clear host tlb reference flag on guest tlb invalidation
 kvm: powerpc: use caching attributes as per linux pte
=20
arch/powerpc/include/asm/kvm_host.h   |    2 +-
arch/powerpc/include/asm/pgtable.h    |   24 ++++++++++++++++
arch/powerpc/include/asm/pte-book3e.h |    2 +-
arch/powerpc/kvm/book3s_hv_rm_mmu.c   |   36 ++++++++----------------
arch/powerpc/kvm/booke.c              |    2 +-
arch/powerpc/kvm/e500.h               |   10 ++++--
arch/powerpc/kvm/e500_mmu_host.c      |   50 =

+++++++++++++++++++--------------

7 files changed, 74 insertions(+), 52 deletions(-)
=20
=20