[RESEND,1/1] KVM: PPC: Book3S: Add MMIO emulation for VMX instructions

Message ID 20180108182931.355-2-joserz@linux.vnet.ibm.com
State New
Headers show
Series
  • Implements MMIO emulation for lvx/stvx instructions
Related show

Commit Message

Jose Ricardo Ziviani Jan. 8, 2018, 6:29 p.m.
This patch provides the MMIO load/store vector indexed
X-Form emulation.

Instructions implemented: lvx, stvx

Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/kvm_host.h   |   2 +
 arch/powerpc/include/asm/kvm_ppc.h    |   4 +
 arch/powerpc/include/asm/ppc-opcode.h |   6 ++
 arch/powerpc/kvm/emulate_loadstore.c  |  32 +++++++
 arch/powerpc/kvm/powerpc.c            | 162 ++++++++++++++++++++++++++++++----
 5 files changed, 189 insertions(+), 17 deletions(-)

Comments

Paul Mackerras Jan. 10, 2018, 10:36 p.m. | #1
On Mon, Jan 08, 2018 at 04:29:31PM -0200, Jose Ricardo Ziviani wrote:
> This patch provides the MMIO load/store vector indexed
> X-Form emulation.
> 
> Instructions implemented: lvx, stvx
> 
> Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>

What testing has been done of this patch?  In particular, what
combinations of endianness of host and guest have been tested?  For a
cross-endian situation (endianness of guest different from host) you
would need to load the two halves of the VMX register image in
reversed order (note that lvx/stvx are different from lxvd2x/stxvd2x
and lxvw4x/stxvw4x in this respect), and I don't see that being done.

Also, lvx/stvx mask off the bottom 4 bits of the EA, and I don't see
that being done.

[snip]

> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 1915e86cef6f..7d0f60359ee0 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -832,23 +832,7 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
>  		kvm->arch.kvm_ops->irq_bypass_del_producer(cons, prod);
>  }
>  
> -#ifdef CONFIG_VSX
> -static inline int kvmppc_get_vsr_dword_offset(int index)
> -{
> -	int offset;
> -
> -	if ((index != 0) && (index != 1))
> -		return -1;
> -
> -#ifdef __BIG_ENDIAN
> -	offset =  index;
> -#else
> -	offset = 1 - index;
> -#endif
> -
> -	return offset;
> -}
> -

Why does this function need to be moved down in the file?

> +#ifdef CONFIG_ALTIVEC
>  static inline int kvmppc_get_vsr_word_offset(int index)
>  {
>  	int offset;
> @@ -864,6 +848,40 @@ static inline int kvmppc_get_vsr_word_offset(int index)
>  	return offset;
>  }
>  
> +static inline void kvmppc_set_vmx_dword(struct kvm_vcpu *vcpu,
> +		u64 gpr)
> +{
> +	int index = vcpu->arch.io_gpr & KVM_MMIO_REG_MASK;
> +	u64 hi = gpr >> 32;
> +	u64 lo = gpr & 0xffffffff;
> +
> +	if (vcpu->arch.mmio_vmx_copy_nums == 1) {
> +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(2)] = hi;
> +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(3)] = lo;
> +	} else if (vcpu->arch.mmio_vmx_copy_nums == 2) {
> +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(0)] = hi;
> +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(1)] = lo;
> +	}

This splitting of the value into hi/lo words looks to me like you're
assuming a big-endian byte ordering.  It looks like it will end up
swapping the words in each half of the register on a little-endian
host (regardless of the endianness of the guest).

> +}
> +#endif /* CONFIG_ALTIVEC */
> +
> +#ifdef CONFIG_VSX
> +static inline int kvmppc_get_vsr_dword_offset(int index)
> +{
> +	int offset;
> +
> +	if ((index != 0) && (index != 1))
> +		return -1;
> +
> +#ifdef __BIG_ENDIAN
> +	offset =  index;
> +#else
> +	offset = 1 - index;
> +#endif
> +
> +	return offset;
> +}
> +
>  static inline void kvmppc_set_vsr_dword(struct kvm_vcpu *vcpu,
>  	u64 gpr)
>  {
> @@ -1027,6 +1045,11 @@ static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
>  				KVMPPC_VSX_COPY_DWORD_LOAD_DUMP)
>  			kvmppc_set_vsr_dword_dump(vcpu, gpr);
>  		break;
> +#endif
> +#ifdef CONFIG_ALTIVEC
> +	case KVM_MMIO_REG_VMX:
> +		kvmppc_set_vmx_dword(vcpu, gpr);
> +		break;
>  #endif
>  	default:
>  		BUG();
> @@ -1307,6 +1330,99 @@ static int kvmppc_emulate_mmio_vsx_loadstore(struct kvm_vcpu *vcpu,
>  }
>  #endif /* CONFIG_VSX */
>  
> +#ifdef CONFIG_ALTIVEC
> +/* handle quadword load access in two halves */
> +int kvmppc_handle_load128_by2x64(struct kvm_run *run, struct kvm_vcpu *vcpu,
> +		unsigned int rt, int is_default_endian)
> +{
> +	enum emulation_result emulated = EMULATE_DONE;
> +
> +	while (vcpu->arch.mmio_vmx_copy_nums) {
> +		emulated = __kvmppc_handle_load(run, vcpu, rt, 8,
> +				is_default_endian, 0);
> +		if (emulated != EMULATE_DONE)
> +			break;
> +
> +		vcpu->arch.mmio_vmx_copy_nums--;
> +	}
> +	return emulated;
> +}
> +
> +static inline int kvmppc_get_vmx_data(struct kvm_vcpu *vcpu, int rs, u64 *val)
> +{
> +
> +	if (vcpu->arch.mmio_vmx_copy_nums == 1) {
> +		*val = VCPU_VSX_VR(vcpu, rs).u[kvmppc_get_vsr_word_offset(2)];
> +		*val = (*val << 32) | VCPU_VSX_VR(vcpu, rs).
> +			u[kvmppc_get_vsr_word_offset(3)];
> +		return 0;
> +	} else if (vcpu->arch.mmio_vmx_copy_nums == 2) {
> +		*val = VCPU_VSX_VR(vcpu, rs).u[kvmppc_get_vsr_word_offset(0)];
> +		*val = (*val << 32) | VCPU_VSX_VR(vcpu, rs).
> +			u[kvmppc_get_vsr_word_offset(1)];
> +		return 0;
> +	}
> +	return -1;
> +}

Once again, the way this puts two word values together to get a
doubleword looks wrong for a little-endian host.

Paul.
Jose Ricardo Ziviani Jan. 10, 2018, 11:19 p.m. | #2
On Thu, Jan 11, 2018 at 09:36:58AM +1100, Paul Mackerras wrote:
> On Mon, Jan 08, 2018 at 04:29:31PM -0200, Jose Ricardo Ziviani wrote:
> > This patch provides the MMIO load/store vector indexed
> > X-Form emulation.
> > 
> > Instructions implemented: lvx, stvx
> > 
> > Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
> 
> What testing has been done of this patch?  In particular, what
> combinations of endianness of host and guest have been tested?  For a
> cross-endian situation (endianness of guest different from host) you
> would need to load the two halves of the VMX register image in
> reversed order (note that lvx/stvx are different from lxvd2x/stxvd2x
> and lxvw4x/stxvw4x in this respect), and I don't see that being done.

Hello! Thank you for reviewing it.

Yes, I tested it with both in little endian mode. You're absolutely
right, I'll review the cross-endian scenario that's not covered indeed.

> 
> Also, lvx/stvx mask off the bottom 4 bits of the EA, and I don't see
> that being done.
> 
> [snip]
> 
> > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> > index 1915e86cef6f..7d0f60359ee0 100644
> > --- a/arch/powerpc/kvm/powerpc.c
> > +++ b/arch/powerpc/kvm/powerpc.c
> > @@ -832,23 +832,7 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
> >  		kvm->arch.kvm_ops->irq_bypass_del_producer(cons, prod);
> >  }
> >  
> > -#ifdef CONFIG_VSX
> > -static inline int kvmppc_get_vsr_dword_offset(int index)
> > -{
> > -	int offset;
> > -
> > -	if ((index != 0) && (index != 1))
> > -		return -1;
> > -
> > -#ifdef __BIG_ENDIAN
> > -	offset =  index;
> > -#else
> > -	offset = 1 - index;
> > -#endif
> > -
> > -	return offset;
> > -}
> > -
> 
> Why does this function need to be moved down in the file?

The main reason is that I need it too but I need it available with
ALTIVEC(1) support, so I changed the guard to ALTIVEC and moved it down
closer to other related functions under the same guard. But I can move
it back if you prefer.

(1)AFAIK it's possible to have ALTIVEC enabled but VSX disabled, not the
other way around.

> 
> > +#ifdef CONFIG_ALTIVEC
> >  static inline int kvmppc_get_vsr_word_offset(int index)
> >  {
> >  	int offset;
> > @@ -864,6 +848,40 @@ static inline int kvmppc_get_vsr_word_offset(int index)
> >  	return offset;
> >  }
> >  
> > +static inline void kvmppc_set_vmx_dword(struct kvm_vcpu *vcpu,
> > +		u64 gpr)
> > +{
> > +	int index = vcpu->arch.io_gpr & KVM_MMIO_REG_MASK;
> > +	u64 hi = gpr >> 32;
> > +	u64 lo = gpr & 0xffffffff;
> > +
> > +	if (vcpu->arch.mmio_vmx_copy_nums == 1) {
> > +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(2)] = hi;
> > +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(3)] = lo;
> > +	} else if (vcpu->arch.mmio_vmx_copy_nums == 2) {
> > +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(0)] = hi;
> > +		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(1)] = lo;
> > +	}
> 
> This splitting of the value into hi/lo words looks to me like you're
> assuming a big-endian byte ordering.  It looks like it will end up
> swapping the words in each half of the register on a little-endian
> host (regardless of the endianness of the guest).

Yep! I focused on VCPU_VSX_VR code to fill the vector correctly but
missed the 64-bit value splitting. I'll fix it and improve the testing,
considering other endian scenario.

> 
> > +}
> > +#endif /* CONFIG_ALTIVEC */
> > +
> > +#ifdef CONFIG_VSX
> > +static inline int kvmppc_get_vsr_dword_offset(int index)
> > +{
> > +	int offset;
> > +
> > +	if ((index != 0) && (index != 1))
> > +		return -1;
> > +
> > +#ifdef __BIG_ENDIAN
> > +	offset =  index;
> > +#else
> > +	offset = 1 - index;
> > +#endif
> > +
> > +	return offset;
> > +}
> > +
> >  static inline void kvmppc_set_vsr_dword(struct kvm_vcpu *vcpu,
> >  	u64 gpr)
> >  {
> > @@ -1027,6 +1045,11 @@ static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
> >  				KVMPPC_VSX_COPY_DWORD_LOAD_DUMP)
> >  			kvmppc_set_vsr_dword_dump(vcpu, gpr);
> >  		break;
> > +#endif
> > +#ifdef CONFIG_ALTIVEC
> > +	case KVM_MMIO_REG_VMX:
> > +		kvmppc_set_vmx_dword(vcpu, gpr);
> > +		break;
> >  #endif
> >  	default:
> >  		BUG();
> > @@ -1307,6 +1330,99 @@ static int kvmppc_emulate_mmio_vsx_loadstore(struct kvm_vcpu *vcpu,
> >  }
> >  #endif /* CONFIG_VSX */
> >  
> > +#ifdef CONFIG_ALTIVEC
> > +/* handle quadword load access in two halves */
> > +int kvmppc_handle_load128_by2x64(struct kvm_run *run, struct kvm_vcpu *vcpu,
> > +		unsigned int rt, int is_default_endian)
> > +{
> > +	enum emulation_result emulated = EMULATE_DONE;
> > +
> > +	while (vcpu->arch.mmio_vmx_copy_nums) {
> > +		emulated = __kvmppc_handle_load(run, vcpu, rt, 8,
> > +				is_default_endian, 0);
> > +		if (emulated != EMULATE_DONE)
> > +			break;
> > +
> > +		vcpu->arch.mmio_vmx_copy_nums--;
> > +	}
> > +	return emulated;
> > +}
> > +
> > +static inline int kvmppc_get_vmx_data(struct kvm_vcpu *vcpu, int rs, u64 *val)
> > +{
> > +
> > +	if (vcpu->arch.mmio_vmx_copy_nums == 1) {
> > +		*val = VCPU_VSX_VR(vcpu, rs).u[kvmppc_get_vsr_word_offset(2)];
> > +		*val = (*val << 32) | VCPU_VSX_VR(vcpu, rs).
> > +			u[kvmppc_get_vsr_word_offset(3)];
> > +		return 0;
> > +	} else if (vcpu->arch.mmio_vmx_copy_nums == 2) {
> > +		*val = VCPU_VSX_VR(vcpu, rs).u[kvmppc_get_vsr_word_offset(0)];
> > +		*val = (*val << 32) | VCPU_VSX_VR(vcpu, rs).
> > +			u[kvmppc_get_vsr_word_offset(1)];
> > +		return 0;
> > +	}
> > +	return -1;
> > +}
> 
> Once again, the way this puts two word values together to get a
> doubleword looks wrong for a little-endian host.

Got it. It's clear the mixed-endianess confusion. I'll fix it, improve
the test cases and send a V2.

Thank you Paul!

> 
> Paul.
> --
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>

Patch

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 3aa5b577cd60..2c14a78c61a4 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -690,6 +690,7 @@  struct kvm_vcpu_arch {
 	u8 mmio_vsx_offset;
 	u8 mmio_vsx_copy_type;
 	u8 mmio_vsx_tx_sx_enabled;
+	u8 mmio_vmx_copy_nums;
 	u8 osi_needed;
 	u8 osi_enabled;
 	u8 papr_enabled;
@@ -800,6 +801,7 @@  struct kvm_vcpu_arch {
 #define KVM_MMIO_REG_QPR	0x0040
 #define KVM_MMIO_REG_FQPR	0x0060
 #define KVM_MMIO_REG_VSX	0x0080
+#define KVM_MMIO_REG_VMX	0x00a0
 
 #define __KVM_HAVE_ARCH_WQP
 #define __KVM_HAVE_CREATE_DEVICE
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 941c2a3f231b..28c203003519 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -81,6 +81,10 @@  extern int kvmppc_handle_loads(struct kvm_run *run, struct kvm_vcpu *vcpu,
 extern int kvmppc_handle_vsx_load(struct kvm_run *run, struct kvm_vcpu *vcpu,
 				unsigned int rt, unsigned int bytes,
 			int is_default_endian, int mmio_sign_extend);
+extern int kvmppc_handle_load128_by2x64(struct kvm_run *run,
+		struct kvm_vcpu *vcpu, unsigned int rt, int is_default_endian);
+extern int kvmppc_handle_store128_by2x64(struct kvm_run *run,
+		struct kvm_vcpu *vcpu, unsigned int rs, int is_default_endian);
 extern int kvmppc_handle_store(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			       u64 val, unsigned int bytes,
 			       int is_default_endian);
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index ce0930d68857..a51febca08c5 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -156,6 +156,12 @@ 
 #define OP_31_XOP_LFDX          599
 #define OP_31_XOP_LFDUX		631
 
+/* VMX Vector Load Instructions */
+#define OP_31_XOP_LVX           103
+
+/* VMX Vector Store Instructions */
+#define OP_31_XOP_STVX          231
+
 #define OP_LWZ  32
 #define OP_STFS 52
 #define OP_STFSU 53
diff --git a/arch/powerpc/kvm/emulate_loadstore.c b/arch/powerpc/kvm/emulate_loadstore.c
index af833531af31..40fbc14809cb 100644
--- a/arch/powerpc/kvm/emulate_loadstore.c
+++ b/arch/powerpc/kvm/emulate_loadstore.c
@@ -58,6 +58,18 @@  static bool kvmppc_check_vsx_disabled(struct kvm_vcpu *vcpu)
 }
 #endif /* CONFIG_VSX */
 
+#ifdef CONFIG_ALTIVEC
+static bool kvmppc_check_altivec_disabled(struct kvm_vcpu *vcpu)
+{
+	if (!(kvmppc_get_msr(vcpu) & MSR_VEC)) {
+		kvmppc_core_queue_vec_unavail(vcpu);
+		return true;
+	}
+
+	return false;
+}
+#endif /* CONFIG_ALTIVEC */
+
 /*
  * XXX to do:
  * lfiwax, lfiwzx
@@ -98,6 +110,7 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 	vcpu->arch.mmio_vsx_copy_type = KVMPPC_VSX_COPY_NONE;
 	vcpu->arch.mmio_sp64_extend = 0;
 	vcpu->arch.mmio_sign_extend = 0;
+	vcpu->arch.mmio_vmx_copy_nums = 0;
 
 	switch (get_op(inst)) {
 	case 31:
@@ -459,6 +472,25 @@  int kvmppc_emulate_loadstore(struct kvm_vcpu *vcpu)
 							 rs, 4, 1);
 			break;
 #endif /* CONFIG_VSX */
+
+#ifdef CONFIG_ALTIVEC
+		case OP_31_XOP_LVX:
+			if (kvmppc_check_altivec_disabled(vcpu))
+				return EMULATE_DONE;
+			vcpu->arch.mmio_vmx_copy_nums = 2;
+			emulated = kvmppc_handle_load128_by2x64(run, vcpu,
+					KVM_MMIO_REG_VMX|rt, 1);
+			break;
+
+		case OP_31_XOP_STVX:
+			if (kvmppc_check_altivec_disabled(vcpu))
+				return EMULATE_DONE;
+			vcpu->arch.mmio_vmx_copy_nums = 2;
+			emulated = kvmppc_handle_store128_by2x64(run, vcpu,
+					rs, 1);
+			break;
+#endif /* CONFIG_ALTIVEC */
+
 		default:
 			emulated = EMULATE_FAIL;
 			break;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 1915e86cef6f..7d0f60359ee0 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -832,23 +832,7 @@  void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
 		kvm->arch.kvm_ops->irq_bypass_del_producer(cons, prod);
 }
 
-#ifdef CONFIG_VSX
-static inline int kvmppc_get_vsr_dword_offset(int index)
-{
-	int offset;
-
-	if ((index != 0) && (index != 1))
-		return -1;
-
-#ifdef __BIG_ENDIAN
-	offset =  index;
-#else
-	offset = 1 - index;
-#endif
-
-	return offset;
-}
-
+#ifdef CONFIG_ALTIVEC
 static inline int kvmppc_get_vsr_word_offset(int index)
 {
 	int offset;
@@ -864,6 +848,40 @@  static inline int kvmppc_get_vsr_word_offset(int index)
 	return offset;
 }
 
+static inline void kvmppc_set_vmx_dword(struct kvm_vcpu *vcpu,
+		u64 gpr)
+{
+	int index = vcpu->arch.io_gpr & KVM_MMIO_REG_MASK;
+	u64 hi = gpr >> 32;
+	u64 lo = gpr & 0xffffffff;
+
+	if (vcpu->arch.mmio_vmx_copy_nums == 1) {
+		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(2)] = hi;
+		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(3)] = lo;
+	} else if (vcpu->arch.mmio_vmx_copy_nums == 2) {
+		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(0)] = hi;
+		VCPU_VSX_VR(vcpu, index).u[kvmppc_get_vsr_word_offset(1)] = lo;
+	}
+}
+#endif /* CONFIG_ALTIVEC */
+
+#ifdef CONFIG_VSX
+static inline int kvmppc_get_vsr_dword_offset(int index)
+{
+	int offset;
+
+	if ((index != 0) && (index != 1))
+		return -1;
+
+#ifdef __BIG_ENDIAN
+	offset =  index;
+#else
+	offset = 1 - index;
+#endif
+
+	return offset;
+}
+
 static inline void kvmppc_set_vsr_dword(struct kvm_vcpu *vcpu,
 	u64 gpr)
 {
@@ -1027,6 +1045,11 @@  static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
 				KVMPPC_VSX_COPY_DWORD_LOAD_DUMP)
 			kvmppc_set_vsr_dword_dump(vcpu, gpr);
 		break;
+#endif
+#ifdef CONFIG_ALTIVEC
+	case KVM_MMIO_REG_VMX:
+		kvmppc_set_vmx_dword(vcpu, gpr);
+		break;
 #endif
 	default:
 		BUG();
@@ -1307,6 +1330,99 @@  static int kvmppc_emulate_mmio_vsx_loadstore(struct kvm_vcpu *vcpu,
 }
 #endif /* CONFIG_VSX */
 
+#ifdef CONFIG_ALTIVEC
+/* handle quadword load access in two halves */
+int kvmppc_handle_load128_by2x64(struct kvm_run *run, struct kvm_vcpu *vcpu,
+		unsigned int rt, int is_default_endian)
+{
+	enum emulation_result emulated = EMULATE_DONE;
+
+	while (vcpu->arch.mmio_vmx_copy_nums) {
+		emulated = __kvmppc_handle_load(run, vcpu, rt, 8,
+				is_default_endian, 0);
+		if (emulated != EMULATE_DONE)
+			break;
+
+		vcpu->arch.mmio_vmx_copy_nums--;
+	}
+	return emulated;
+}
+
+static inline int kvmppc_get_vmx_data(struct kvm_vcpu *vcpu, int rs, u64 *val)
+{
+
+	if (vcpu->arch.mmio_vmx_copy_nums == 1) {
+		*val = VCPU_VSX_VR(vcpu, rs).u[kvmppc_get_vsr_word_offset(2)];
+		*val = (*val << 32) | VCPU_VSX_VR(vcpu, rs).
+			u[kvmppc_get_vsr_word_offset(3)];
+		return 0;
+	} else if (vcpu->arch.mmio_vmx_copy_nums == 2) {
+		*val = VCPU_VSX_VR(vcpu, rs).u[kvmppc_get_vsr_word_offset(0)];
+		*val = (*val << 32) | VCPU_VSX_VR(vcpu, rs).
+			u[kvmppc_get_vsr_word_offset(1)];
+		return 0;
+	}
+	return -1;
+}
+
+/* handle quadword store in two halves */
+int kvmppc_handle_store128_by2x64(struct kvm_run *run, struct kvm_vcpu *vcpu,
+		unsigned int rs, int is_default_endian)
+{
+	u64 val = 0;
+	enum emulation_result emulated = EMULATE_DONE;
+
+	vcpu->arch.io_gpr = rs;
+
+	while (vcpu->arch.mmio_vmx_copy_nums) {
+		if (kvmppc_get_vmx_data(vcpu, rs, &val) == -1)
+			return EMULATE_FAIL;
+
+		emulated = kvmppc_handle_store(run, vcpu, val, 8,
+				is_default_endian);
+		if (emulated != EMULATE_DONE)
+			break;
+
+		vcpu->arch.mmio_vmx_copy_nums--;
+	}
+	return emulated;
+}
+
+static int kvmppc_emulate_mmio_vmx_loadstore(struct kvm_vcpu *vcpu,
+		struct kvm_run *run)
+{
+	enum emulation_result emulated = EMULATE_FAIL;
+	int r;
+
+	vcpu->arch.paddr_accessed += run->mmio.len;
+
+	if (!vcpu->mmio_is_write) {
+		emulated = kvmppc_handle_load128_by2x64(run, vcpu,
+				vcpu->arch.io_gpr, 1);
+	} else {
+		emulated = kvmppc_handle_store128_by2x64(run, vcpu,
+				vcpu->arch.io_gpr, 1);
+	}
+
+	switch (emulated) {
+	case EMULATE_DO_MMIO:
+		run->exit_reason = KVM_EXIT_MMIO;
+		r = RESUME_HOST;
+		break;
+	case EMULATE_FAIL:
+		pr_info("KVM: MMIO emulation failed (VMX repeat)\n");
+		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+		r = RESUME_HOST;
+		break;
+	default:
+		r = RESUME_GUEST;
+		break;
+	}
+	return r;
+}
+#endif /* CONFIG_ALTIVEC */
+
 int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu, struct kvm_one_reg *reg)
 {
 	int r = 0;
@@ -1425,6 +1541,18 @@  int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 				return r;
 			}
 		}
+#endif
+#ifdef CONFIG_ALTIVEC
+		if (vcpu->arch.mmio_vmx_copy_nums > 0)
+			vcpu->arch.mmio_vmx_copy_nums--;
+
+		if (vcpu->arch.mmio_vmx_copy_nums > 0) {
+			r = kvmppc_emulate_mmio_vmx_loadstore(vcpu, run);
+			if (r == RESUME_HOST) {
+				vcpu->mmio_needed = 1;
+				return r;
+			}
+		}
 #endif
 	} else if (vcpu->arch.osi_needed) {
 		u64 *gprs = run->osi.gprs;