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

[PATCH 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.

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   | 30 ++++++++++++++++++++++--------
 2 files changed, 24 insertions(+), 8 deletions(-)

-- 
2.5.5

[PATCH 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 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).

Finally the PCR value is masked based on the bits of the register which the
current processor is actually aware of.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
---
 arch/powerpc/kvm/book3s_hv.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 3686471..f9ae3fb 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;
+			pcr = PCR_ARCH_207 | PCR_ARCH_206 | PCR_ARCH_205;
 			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;
+			pcr = PCR_ARCH_207 | PCR_ARCH_206;
 			break;
 		case PVR_ARCH_207:
+			/* Must be at least v2.07 to emulate it */
+			if (!cpu_has_feature(CPU_FTR_ARCH_207S))
+				return -EINVAL;
+			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;
 		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;
-		}
+		/*
+		 * Mask the pcr bits which the current processor knows about
+		 * v2.06 and above knows about the v2.05 compat bit
+		 * v2,07 and above knows about the v2.06 compat bit
+		 * v3.00 and above knows about the v2.07 compat bit
+		 */
+		pcr &= (cpu_has_feature(CPU_FTR_ARCH_300) << 3) |
+			(cpu_has_feature(CPU_FTR_ARCH_207S) << 2) |
+			(cpu_has_feature(CPU_FTR_ARCH_206) << 1);
 	}
 
 	spin_lock(&vc->lock);
-- 
2.5.5

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

[Michael Ellerman]

Suraj Jitindar Singh <sjitindarsingh@gmail.com> writes:
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 3686471..f9ae3fb 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;
> +			pcr = PCR_ARCH_207 | PCR_ARCH_206 | PCR_ARCH_205;
>  			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;
> +			pcr = PCR_ARCH_207 | PCR_ARCH_206;
>  			break;
>  		case PVR_ARCH_207:
> +			/* Must be at least v2.07 to emulate it */
> +			if (!cpu_has_feature(CPU_FTR_ARCH_207S))
> +				return -EINVAL;
> +			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;
>  		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;
> -		}
> +		/*
> +		 * Mask the pcr bits which the current processor knows about
> +		 * v2.06 and above knows about the v2.05 compat bit
> +		 * v2,07 and above knows about the v2.06 compat bit
> +		 * v3.00 and above knows about the v2.07 compat bit
> +		 */
> +		pcr &= (cpu_has_feature(CPU_FTR_ARCH_300) << 3) |
> +			(cpu_has_feature(CPU_FTR_ARCH_207S) << 2) |
> +			(cpu_has_feature(CPU_FTR_ARCH_206) << 1);

cpu_has_feature() returns a bool, so shifting the result of it is
dubious. It also uses jump labels these days, so I have no idea what
code that is going to generate.

Better to just do it the simple way IMHO.

cheers