Patchwork [1/2] KVM: PPC: Book3S HV: Correct tlbie usage

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Submitter Paul Mackerras
Date July 8, 2013, 10:08 a.m.
Message ID <20130708100825.GC24032@iris.ozlabs.ibm.com>
Download mbox | patch
Permalink /patch/257512/
State New
Headers show

Comments

Paul Mackerras - July 8, 2013, 10:08 a.m.
This corrects the usage of the tlbie (TLB invalidate entry) instruction
in HV KVM.  The tlbie instruction changed between PPC970 and POWER7.
On the PPC970, the bit to select large vs. small page is in the instruction,
not in the RB register value.  This changes the code to use the correct
form on PPC970.

On POWER7 we were calculating the AVAL (Abbreviated Virtual Address, Lower)
field of the RB value incorrectly for 64k pages.  This fixes it.

Since we now have several cases to handle for the tlbie instruction, this
factors out the code to do a sequence of tlbies into a new function,
do_tlbies(), and calls that from the various places where the code was
doing tlbie instructions inline.  It also makes kvmppc_h_bulk_remove()
use the same global_invalidates() function for determining whether to do
local or global TLB invalidations as is used in other places, for
consistency, and also to make sure that kvm->arch.need_tlb_flush gets
updated properly.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: stable@vger.kernel.org
---
 arch/powerpc/include/asm/kvm_book3s_64.h |   2 +-
 arch/powerpc/kvm/book3s_hv_rm_mmu.c      | 139 ++++++++++++++++++-------------
 2 files changed, 82 insertions(+), 59 deletions(-)
Alexander Graf - July 10, 2013, 11:15 a.m.
On 08.07.2013, at 12:08, Paul Mackerras wrote:

> This corrects the usage of the tlbie (TLB invalidate entry) instruction
> in HV KVM.  The tlbie instruction changed between PPC970 and POWER7.
> On the PPC970, the bit to select large vs. small page is in the instruction,
> not in the RB register value.  This changes the code to use the correct
> form on PPC970.
> 
> On POWER7 we were calculating the AVAL (Abbreviated Virtual Address, Lower)
> field of the RB value incorrectly for 64k pages.  This fixes it.
> 
> Since we now have several cases to handle for the tlbie instruction, this
> factors out the code to do a sequence of tlbies into a new function,
> do_tlbies(), and calls that from the various places where the code was
> doing tlbie instructions inline.  It also makes kvmppc_h_bulk_remove()
> use the same global_invalidates() function for determining whether to do
> local or global TLB invalidations as is used in other places, for
> consistency, and also to make sure that kvm->arch.need_tlb_flush gets
> updated properly.
> 
> Signed-off-by: Paul Mackerras <paulus@samba.org>
> Cc: stable@vger.kernel.org

Thanks, applied both to kvm-ppc-queue.


Alex

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Aneesh Kumar K.V - July 17, 2013, 10:40 a.m.
Paul Mackerras <paulus@samba.org> writes:

> This corrects the usage of the tlbie (TLB invalidate entry) instruction
> in HV KVM.  The tlbie instruction changed between PPC970 and POWER7.
> On the PPC970, the bit to select large vs. small page is in the instruction,
> not in the RB register value.  This changes the code to use the correct
> form on PPC970.

I guess we need a similar fix for __tlbiel ?

>
> On POWER7 we were calculating the AVAL (Abbreviated Virtual Address, Lower)
> field of the RB value incorrectly for 64k pages.  This fixes it.
>
> Since we now have several cases to handle for the tlbie instruction, this
> factors out the code to do a sequence of tlbies into a new function,
> do_tlbies(), and calls that from the various places where the code was
> doing tlbie instructions inline.  It also makes kvmppc_h_bulk_remove()
> use the same global_invalidates() function for determining whether to do
> local or global TLB invalidations as is used in other places, for
> consistency, and also to make sure that kvm->arch.need_tlb_flush gets
> updated properly.
>
> Signed-off-by: Paul Mackerras <paulus@samba.org>
> Cc: stable@vger.kernel.org
> ---
>  arch/powerpc/include/asm/kvm_book3s_64.h |   2 +-
>  arch/powerpc/kvm/book3s_hv_rm_mmu.c      | 139 ++++++++++++++++++-------------
>  2 files changed, 82 insertions(+), 59 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
> index 9c1ff33..dc6b84a 100644
> --- a/arch/powerpc/include/asm/kvm_book3s_64.h
> +++ b/arch/powerpc/include/asm/kvm_book3s_64.h
> @@ -100,7 +100,7 @@ static inline unsigned long compute_tlbie_rb(unsigned long v, unsigned long r,
>  			/* (masks depend on page size) */
>  			rb |= 0x1000;		/* page encoding in LP field */
>  			rb |= (va_low & 0x7f) << 16; /* 7b of VA in AVA/LP field */
> -			rb |= (va_low & 0xfe);	/* AVAL field (P7 doesn't seem to care) */
> +			rb |= ((va_low << 4) & 0xf0);	/* AVAL field
> (P7 doesn't seem to care) */


Can you explain this more ? Why shift by 4 ? and what about the three
bits ('e' part of 0xfe) ? 

>  		}
>  	} else {
>  		/* 4kB page */
> diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> index 6dcbb49..105b00f 100644
> --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> @@ -385,6 +385,80 @@ static inline int try_lock_tlbie(unsigned int *lock)
>  	return old == 0;
>  }
>  

-aneesh

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Patch

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 9c1ff33..dc6b84a 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -100,7 +100,7 @@  static inline unsigned long compute_tlbie_rb(unsigned long v, unsigned long r,
 			/* (masks depend on page size) */
 			rb |= 0x1000;		/* page encoding in LP field */
 			rb |= (va_low & 0x7f) << 16; /* 7b of VA in AVA/LP field */
-			rb |= (va_low & 0xfe);	/* AVAL field (P7 doesn't seem to care) */
+			rb |= ((va_low << 4) & 0xf0);	/* AVAL field (P7 doesn't seem to care) */
 		}
 	} else {
 		/* 4kB page */
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 6dcbb49..105b00f 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -385,6 +385,80 @@  static inline int try_lock_tlbie(unsigned int *lock)
 	return old == 0;
 }
 
+/*
+ * tlbie/tlbiel is a bit different on the PPC970 compared to later
+ * processors such as POWER7; the large page bit is in the instruction
+ * not RB, and the top 16 bits and the bottom 12 bits of the VA
+ * in RB must be 0.
+ */
+static void do_tlbies_970(struct kvm *kvm, unsigned long *rbvalues,
+			  long npages, int global, bool need_sync)
+{
+	long i;
+
+	if (global) {
+		while (!try_lock_tlbie(&kvm->arch.tlbie_lock))
+			cpu_relax();
+		if (need_sync)
+			asm volatile("ptesync" : : : "memory");
+		for (i = 0; i < npages; ++i) {
+			unsigned long rb = rbvalues[i];
+
+			if (rb & 1)		/* large page */
+				asm volatile("tlbie %0,1" : :
+					     "r" (rb & 0x0000fffffffff000ul));
+			else
+				asm volatile("tlbie %0,0" : :
+					     "r" (rb & 0x0000fffffffff000ul));
+		}
+		asm volatile("eieio; tlbsync; ptesync" : : : "memory");
+		kvm->arch.tlbie_lock = 0;
+	} else {
+		if (need_sync)
+			asm volatile("ptesync" : : : "memory");
+		for (i = 0; i < npages; ++i) {
+			unsigned long rb = rbvalues[i];
+
+			if (rb & 1)		/* large page */
+				asm volatile("tlbiel %0,1" : :
+					     "r" (rb & 0x0000fffffffff000ul));
+			else
+				asm volatile("tlbiel %0,0" : :
+					     "r" (rb & 0x0000fffffffff000ul));
+		}
+		asm volatile("ptesync" : : : "memory");
+	}
+}
+
+static void do_tlbies(struct kvm *kvm, unsigned long *rbvalues,
+		      long npages, int global, bool need_sync)
+{
+	long i;
+
+	if (cpu_has_feature(CPU_FTR_ARCH_201)) {
+		/* PPC970 tlbie instruction is a bit different */
+		do_tlbies_970(kvm, rbvalues, npages, global, need_sync);
+		return;
+	}
+	if (global) {
+		while (!try_lock_tlbie(&kvm->arch.tlbie_lock))
+			cpu_relax();
+		if (need_sync)
+			asm volatile("ptesync" : : : "memory");
+		for (i = 0; i < npages; ++i)
+			asm volatile(PPC_TLBIE(%1,%0) : :
+				     "r" (rbvalues[i]), "r" (kvm->arch.lpid));
+		asm volatile("eieio; tlbsync; ptesync" : : : "memory");
+		kvm->arch.tlbie_lock = 0;
+	} else {
+		if (need_sync)
+			asm volatile("ptesync" : : : "memory");
+		for (i = 0; i < npages; ++i)
+			asm volatile("tlbiel %0" : : "r" (rbvalues[i]));
+		asm volatile("ptesync" : : : "memory");
+	}
+}
+
 long kvmppc_do_h_remove(struct kvm *kvm, unsigned long flags,
 			unsigned long pte_index, unsigned long avpn,
 			unsigned long *hpret)
@@ -410,19 +484,7 @@  long kvmppc_do_h_remove(struct kvm *kvm, unsigned long flags,
 	if (v & HPTE_V_VALID) {
 		hpte[0] &= ~HPTE_V_VALID;
 		rb = compute_tlbie_rb(v, hpte[1], pte_index);
-		if (global_invalidates(kvm, flags)) {
-			while (!try_lock_tlbie(&kvm->arch.tlbie_lock))
-				cpu_relax();
-			asm volatile("ptesync" : : : "memory");
-			asm volatile(PPC_TLBIE(%1,%0)"; eieio; tlbsync"
-				     : : "r" (rb), "r" (kvm->arch.lpid));
-			asm volatile("ptesync" : : : "memory");
-			kvm->arch.tlbie_lock = 0;
-		} else {
-			asm volatile("ptesync" : : : "memory");
-			asm volatile("tlbiel %0" : : "r" (rb));
-			asm volatile("ptesync" : : : "memory");
-		}
+		do_tlbies(kvm, &rb, 1, global_invalidates(kvm, flags), true);
 		/* Read PTE low word after tlbie to get final R/C values */
 		remove_revmap_chain(kvm, pte_index, rev, v, hpte[1]);
 	}
@@ -450,12 +512,11 @@  long kvmppc_h_bulk_remove(struct kvm_vcpu *vcpu)
 	unsigned long *hp, *hptes[4], tlbrb[4];
 	long int i, j, k, n, found, indexes[4];
 	unsigned long flags, req, pte_index, rcbits;
-	long int local = 0;
+	int global;
 	long int ret = H_SUCCESS;
 	struct revmap_entry *rev, *revs[4];
 
-	if (atomic_read(&kvm->online_vcpus) == 1)
-		local = 1;
+	global = global_invalidates(kvm, 0);
 	for (i = 0; i < 4 && ret == H_SUCCESS; ) {
 		n = 0;
 		for (; i < 4; ++i) {
@@ -531,22 +592,7 @@  long kvmppc_h_bulk_remove(struct kvm_vcpu *vcpu)
 			break;
 
 		/* Now that we've collected a batch, do the tlbies */
-		if (!local) {
-			while(!try_lock_tlbie(&kvm->arch.tlbie_lock))
-				cpu_relax();
-			asm volatile("ptesync" : : : "memory");
-			for (k = 0; k < n; ++k)
-				asm volatile(PPC_TLBIE(%1,%0) : :
-					     "r" (tlbrb[k]),
-					     "r" (kvm->arch.lpid));
-			asm volatile("eieio; tlbsync; ptesync" : : : "memory");
-			kvm->arch.tlbie_lock = 0;
-		} else {
-			asm volatile("ptesync" : : : "memory");
-			for (k = 0; k < n; ++k)
-				asm volatile("tlbiel %0" : : "r" (tlbrb[k]));
-			asm volatile("ptesync" : : : "memory");
-		}
+		do_tlbies(kvm, tlbrb, n, global, true);
 
 		/* Read PTE low words after tlbie to get final R/C values */
 		for (k = 0; k < n; ++k) {
@@ -605,19 +651,7 @@  long kvmppc_h_protect(struct kvm_vcpu *vcpu, unsigned long flags,
 	if (v & HPTE_V_VALID) {
 		rb = compute_tlbie_rb(v, r, pte_index);
 		hpte[0] = v & ~HPTE_V_VALID;
-		if (global_invalidates(kvm, flags)) {
-			while(!try_lock_tlbie(&kvm->arch.tlbie_lock))
-				cpu_relax();
-			asm volatile("ptesync" : : : "memory");
-			asm volatile(PPC_TLBIE(%1,%0)"; eieio; tlbsync"
-				     : : "r" (rb), "r" (kvm->arch.lpid));
-			asm volatile("ptesync" : : : "memory");
-			kvm->arch.tlbie_lock = 0;
-		} else {
-			asm volatile("ptesync" : : : "memory");
-			asm volatile("tlbiel %0" : : "r" (rb));
-			asm volatile("ptesync" : : : "memory");
-		}
+		do_tlbies(kvm, &rb, 1, global_invalidates(kvm, flags), true);
 		/*
 		 * If the host has this page as readonly but the guest
 		 * wants to make it read/write, reduce the permissions.
@@ -688,13 +722,7 @@  void kvmppc_invalidate_hpte(struct kvm *kvm, unsigned long *hptep,
 
 	hptep[0] &= ~HPTE_V_VALID;
 	rb = compute_tlbie_rb(hptep[0], hptep[1], pte_index);
-	while (!try_lock_tlbie(&kvm->arch.tlbie_lock))
-		cpu_relax();
-	asm volatile("ptesync" : : : "memory");
-	asm volatile(PPC_TLBIE(%1,%0)"; eieio; tlbsync"
-		     : : "r" (rb), "r" (kvm->arch.lpid));
-	asm volatile("ptesync" : : : "memory");
-	kvm->arch.tlbie_lock = 0;
+	do_tlbies(kvm, &rb, 1, 1, true);
 }
 EXPORT_SYMBOL_GPL(kvmppc_invalidate_hpte);
 
@@ -708,12 +736,7 @@  void kvmppc_clear_ref_hpte(struct kvm *kvm, unsigned long *hptep,
 	rbyte = (hptep[1] & ~HPTE_R_R) >> 8;
 	/* modify only the second-last byte, which contains the ref bit */
 	*((char *)hptep + 14) = rbyte;
-	while (!try_lock_tlbie(&kvm->arch.tlbie_lock))
-		cpu_relax();
-	asm volatile(PPC_TLBIE(%1,%0)"; eieio; tlbsync"
-		     : : "r" (rb), "r" (kvm->arch.lpid));
-	asm volatile("ptesync" : : : "memory");
-	kvm->arch.tlbie_lock = 0;
+	do_tlbies(kvm, &rb, 1, 1, false);
 }
 EXPORT_SYMBOL_GPL(kvmppc_clear_ref_hpte);