[PATCH V2 0/2] powerpc: add support for ISA v2.07 compat level

[PATCH V2 0/2] powerpc: add support for ISA v2.07 compat level

[Suraj Jitindar Singh]

Version v3.00 of the ISA added a new compat level to the processor
compatibility register (PCR), an ISA v2.07 compatibility mode.

Upstream QEMU already supports this so it may as well go into the kernel
now.

Change Log:

V1 -> V2:
- Reworked logic to set and mask the PCR, no functional change

Suraj Jitindar Singh (2):
  powerpc: Define new ISA v3.00 logical PVR value and PCR register value
  powerpc/kvm: Update kvmppc_set_arch_compat() for ISA v3.00

 arch/powerpc/include/asm/reg.h |  2 ++
 arch/powerpc/kvm/book3s_hv.c   | 32 +++++++++++++++++++++++---------
 2 files changed, 25 insertions(+), 9 deletions(-)

-- 
2.5.5

[PATCH V2 1/2] powerpc: Define new ISA v3.00 logical PVR value and PCR register value

[Suraj Jitindar Singh]

ISA 3.00 adds the logical PVR value 0x0f000005, so add a definition for
this.

Define PCR_ARCH_207 to reflect ISA 2.07 compatibility mode in the processor
compatibility register (PCR).

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
---
 arch/powerpc/include/asm/reg.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 9cd4e8c..74c8079 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -377,6 +377,7 @@
 #define   PCR_VEC_DIS	(1ul << (63-0))	/* Vec. disable (bit NA since POWER8) */
 #define   PCR_VSX_DIS	(1ul << (63-1))	/* VSX disable (bit NA since POWER8) */
 #define   PCR_TM_DIS	(1ul << (63-2))	/* Trans. memory disable (POWER8) */
+#define   PCR_ARCH_207	0x8		/* Architecture 2.07 */
 #define   PCR_ARCH_206	0x4		/* Architecture 2.06 */
 #define   PCR_ARCH_205	0x2		/* Architecture 2.05 */
 #define	SPRN_HEIR	0x153	/* Hypervisor Emulated Instruction Register */
@@ -1218,6 +1219,7 @@
 #define PVR_ARCH_206	0x0f000003
 #define PVR_ARCH_206p	0x0f100003
 #define PVR_ARCH_207	0x0f000004
+#define PVR_ARCH_300	0x0f000005
 
 /* Macros for setting and retrieving special purpose registers */
 #ifndef __ASSEMBLY__
-- 
2.5.5

[PATCH V2 2/2] powerpc/kvm: Update kvmppc_set_arch_compat() for ISA v3.00

[Suraj Jitindar Singh]

The function kvmppc_set_arch_compat() is used to determine the value of the
processor compatibility register (PCR) for a guest running in a given
compatibility mode. There is currently no support for v3.00 of the ISA.

Add support for v3.00 of the ISA which adds an ISA v2.07 compatilibity mode
to the PCR.

We also add a check to ensure the processor we are running on is capable of
emulating the chosen processor (for example a POWER7 cannot emulate a
POWER8, similarly with a POWER8 and a POWER9).

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
---
 arch/powerpc/kvm/book3s_hv.c | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 3686471..24681e7 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -311,24 +311,38 @@ static int kvmppc_set_arch_compat(struct kvm_vcpu *vcpu, u32 arch_compat)
 			 * If an arch bit is set in PCR, all the defined
 			 * higher-order arch bits also have to be set.
 			 */
-			pcr = PCR_ARCH_206 | PCR_ARCH_205;
+			if (cpu_has_feature(CPU_FTR_ARCH_206))
+				pcr |= PCR_ARCH_205;
+			if (cpu_has_feature(CPU_FTR_ARCH_207S))
+				pcr |= PCR_ARCH_206;
+			if (cpu_has_feature(CPU_FTR_ARCH_300))
+				pcr |= PCR_ARCH_207;
 			break;
 		case PVR_ARCH_206:
 		case PVR_ARCH_206p:
-			pcr = PCR_ARCH_206;
+			/* Must be at least v2.06 to (emulate) it */
+			if (!cpu_has_feature(CPU_FTR_ARCH_206))
+				return -EINVAL;
+			if (cpu_has_feature(CPU_FTR_ARCH_207S))
+				pcr |= PCR_ARCH_206;
+			if (cpu_has_feature(CPU_FTR_ARCH_300))
+				pcr |= PCR_ARCH_207;
 			break;
 		case PVR_ARCH_207:
+			/* Must be at least v2.07 to (emulate) it */
+			if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+				return -EINVAL;
+			if (cpu_has_feature(CPU_FTR_ARCH_300))
+				pcr |= PCR_ARCH_207;
+			break;
+		case PVR_ARCH_300:
+			/* Must be at least v3.00 to (emulate) it */
+			if (!cpu_has_feature(CPU_FTR_ARCH_300))
+				return -EINVAL;
 			break;
 		default:
 			return -EINVAL;
 		}
-
-		if (!cpu_has_feature(CPU_FTR_ARCH_207S)) {
-			/* POWER7 can't emulate POWER8 */
-			if (!(pcr & PCR_ARCH_206))
-				return -EINVAL;
-			pcr &= ~PCR_ARCH_206;
-		}
 	}
 
 	spin_lock(&vc->lock);
-- 
2.5.5

Re: [PATCH V2 2/2] powerpc/kvm: Update kvmppc_set_arch_compat() for ISA v3.00

[Paul Mackerras]

On Mon, Oct 31, 2016 at 11:28:23AM +1100, Suraj Jitindar Singh wrote:
> The function kvmppc_set_arch_compat() is used to determine the value of the
> processor compatibility register (PCR) for a guest running in a given
> compatibility mode. There is currently no support for v3.00 of the ISA.
> 
> Add support for v3.00 of the ISA which adds an ISA v2.07 compatilibity mode
> to the PCR.
> 
> We also add a check to ensure the processor we are running on is capable of
> emulating the chosen processor (for example a POWER7 cannot emulate a
> POWER8, similarly with a POWER8 and a POWER9).
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> ---
>  arch/powerpc/kvm/book3s_hv.c | 32 +++++++++++++++++++++++---------
>  1 file changed, 23 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 3686471..24681e7 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -311,24 +311,38 @@ static int kvmppc_set_arch_compat(struct kvm_vcpu *vcpu, u32 arch_compat)
>  			 * If an arch bit is set in PCR, all the defined
>  			 * higher-order arch bits also have to be set.
>  			 */
> -			pcr = PCR_ARCH_206 | PCR_ARCH_205;
> +			if (cpu_has_feature(CPU_FTR_ARCH_206))
> +				pcr |= PCR_ARCH_205;
> +			if (cpu_has_feature(CPU_FTR_ARCH_207S))
> +				pcr |= PCR_ARCH_206;
> +			if (cpu_has_feature(CPU_FTR_ARCH_300))
> +				pcr |= PCR_ARCH_207;
>  			break;
>  		case PVR_ARCH_206:
>  		case PVR_ARCH_206p:
> -			pcr = PCR_ARCH_206;
> +			/* Must be at least v2.06 to (emulate) it */
> +			if (!cpu_has_feature(CPU_FTR_ARCH_206))
> +				return -EINVAL;
> +			if (cpu_has_feature(CPU_FTR_ARCH_207S))
> +				pcr |= PCR_ARCH_206;
> +			if (cpu_has_feature(CPU_FTR_ARCH_300))
> +				pcr |= PCR_ARCH_207;
>  			break;
>  		case PVR_ARCH_207:
> +			/* Must be at least v2.07 to (emulate) it */
> +			if (!cpu_has_feature(CPU_FTR_ARCH_207S))
> +				return -EINVAL;
> +			if (cpu_has_feature(CPU_FTR_ARCH_300))
> +				pcr |= PCR_ARCH_207;
> +			break;
> +		case PVR_ARCH_300:
> +			/* Must be at least v3.00 to (emulate) it */
> +			if (!cpu_has_feature(CPU_FTR_ARCH_300))
> +				return -EINVAL;
>  			break;

I can't help thinking that the repetitive structure of the lines
you're adding must imply a regularity that could be expressed more
concisely.  If you defined a dummy PCR_ARCH_300 bit as 0x10, perhaps
you could do something like this:

	if (cpu_has_feature(CPU_FTR_ARCH_300))
		host_pcr_bit = PCR_ARCH_300;
	else if (cpu_has_feature(CPU_FTR_ARCH_207S))
		host_pcr_bit = PCR_ARCH_207;
	else
		host_pcr_bit = PCR_ARCH_206;

	switch (arch_compat) {
	case PVR_ARCH_205:
		guest_pcr_bit = PCR_ARCH_205;
		break;
	case PVR_ARCH_206:
		guest_pcr_bit = PCR_ARCH_206;
		break;
	case PVR_ARCH_207:
	case PVR_ARCH_207S:
		guest_pcr_bit = PCR_ARCH_207;
		break;
	case PVR_ARCH_300:
		guest_pcr_bit = PCR_ARCH_300;
		break;
	default:
		return -EINVAL;
	}

	if (guest_pcr_bit > host_pcr_bit)
		return -EINVAL;

	pcr = host_pcr_bit - guest_pcr_bit;

The translation from arch_compat to guest_pcr_bit might look neater as
a table lookup on the low bits of arch_compat, after a bounds check.

Paul.

Re: [PATCH V2 2/2] powerpc/kvm: Update kvmppc_set_arch_compat() for ISA v3.00

[Suraj Jitindar Singh]

On Mon, 2016-10-31 at 16:44 +1100, Paul Mackerras wrote:
> On Mon, Oct 31, 2016 at 11:28:23AM +1100, Suraj Jitindar Singh wrote:
> > 
> > The function kvmppc_set_arch_compat() is used to determine the
> > value of the
> > processor compatibility register (PCR) for a guest running in a
> > given
> > compatibility mode. There is currently no support for v3.00 of the
> > ISA.
> > 
> > Add support for v3.00 of the ISA which adds an ISA v2.07
> > compatilibity mode
> > to the PCR.
> > 
> > We also add a check to ensure the processor we are running on is
> > capable of
> > emulating the chosen processor (for example a POWER7 cannot emulate
> > a
> > POWER8, similarly with a POWER8 and a POWER9).
> > 
> > Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> > ---
> >  arch/powerpc/kvm/book3s_hv.c | 32 +++++++++++++++++++++++---------
> >  1 file changed, 23 insertions(+), 9 deletions(-)
> > 
> > diff --git a/arch/powerpc/kvm/book3s_hv.c
> > b/arch/powerpc/kvm/book3s_hv.c
> > index 3686471..24681e7 100644
> > --- a/arch/powerpc/kvm/book3s_hv.c
> > +++ b/arch/powerpc/kvm/book3s_hv.c
> > @@ -311,24 +311,38 @@ static int kvmppc_set_arch_compat(struct
> > kvm_vcpu *vcpu, u32 arch_compat)
> >  			 * If an arch bit is set in PCR, all the
> > defined
> >  			 * higher-order arch bits also have to be
> > set.
> >  			 */
> > -			pcr = PCR_ARCH_206 | PCR_ARCH_205;
> > +			if (cpu_has_feature(CPU_FTR_ARCH_206))
> > +				pcr |= PCR_ARCH_205;
> > +			if (cpu_has_feature(CPU_FTR_ARCH_207S))
> > +				pcr |= PCR_ARCH_206;
> > +			if (cpu_has_feature(CPU_FTR_ARCH_300))
> > +				pcr |= PCR_ARCH_207;
> >  			break;
> >  		case PVR_ARCH_206:
> >  		case PVR_ARCH_206p:
> > -			pcr = PCR_ARCH_206;
> > +			/* Must be at least v2.06 to (emulate) it
> > */
> > +			if (!cpu_has_feature(CPU_FTR_ARCH_206))
> > +				return -EINVAL;
> > +			if (cpu_has_feature(CPU_FTR_ARCH_207S))
> > +				pcr |= PCR_ARCH_206;
> > +			if (cpu_has_feature(CPU_FTR_ARCH_300))
> > +				pcr |= PCR_ARCH_207;
> >  			break;
> >  		case PVR_ARCH_207:
> > +			/* Must be at least v2.07 to (emulate) it
> > */
> > +			if (!cpu_has_feature(CPU_FTR_ARCH_207S))
> > +				return -EINVAL;
> > +			if (cpu_has_feature(CPU_FTR_ARCH_300))
> > +				pcr |= PCR_ARCH_207;
> > +			break;
> > +		case PVR_ARCH_300:
> > +			/* Must be at least v3.00 to (emulate) it
> > */
> > +			if (!cpu_has_feature(CPU_FTR_ARCH_300))
> > +				return -EINVAL;
> >  			break;
> I can't help thinking that the repetitive structure of the lines
> you're adding must imply a regularity that could be expressed more
> concisely.  If you defined a dummy PCR_ARCH_300 bit as 0x10, perhaps
> you could do something like this:
> 
> 	if (cpu_has_feature(CPU_FTR_ARCH_300))
> 		host_pcr_bit = PCR_ARCH_300;
> 	else if (cpu_has_feature(CPU_FTR_ARCH_207S))
> 		host_pcr_bit = PCR_ARCH_207;
> 	else
else if
> 		host_pcr_bit = PCR_ARCH_206;
else
	host_pcr_bit = PCR_ARCH_205;
> 
> 	switch (arch_compat) {
> 	case PVR_ARCH_205:
> 		guest_pcr_bit = PCR_ARCH_205;
> 		break;
> 	case PVR_ARCH_206:
> 		guest_pcr_bit = PCR_ARCH_206;
> 		break;
> 	case PVR_ARCH_207:
> 	case PVR_ARCH_207S:
> 		guest_pcr_bit = PCR_ARCH_207;
> 		break;
> 	case PVR_ARCH_300:
> 		guest_pcr_bit = PCR_ARCH_300;
> 		break;
> 	default:
> 		return -EINVAL;
> 	}
> 
> 	if (guest_pcr_bit > host_pcr_bit)
> 		return -EINVAL;
> 
> 	pcr = host_pcr_bit - guest_pcr_bit;
That approach is simpler and more extensible, I guess I don't really
like that it relies on the assumption that the PCR bits remain
consecutive and breaks if that assumption becomes invalid, which may
never be the case. I guess we can assume they will be for now and fix
it in the event that ever changes.
> 
> The translation from arch_compat to guest_pcr_bit might look neater
> as
> a table lookup on the low bits of arch_compat, after a bounds check.
Is that really necessary? I don't see the benefit and the code is more
readable in it's current form IMO.

Something like this?

unsigned long guest_pcr_bits = {0,              /* 0 */ 
                                0,              /* 1 */ 
                                PCR_ARCH_205,   /* 0x0F000002 */
                                PCR_ARCH_206,   /* 0x0F000003 */
                                PCR_ARCH_207,   /* 0x0F000004 */
                                PCR_ARCH_300 }; /* 0x0F000005 */
if (arch_compat <= PVR_ARCH_300 && arch_compat >= PVR_ARCH_205)
        guest_pcr_bit = guest_pcr_bits[arch_compat & 0xF]; 
else    
        return -EINVAL;
> 
> Paul.