On 28.01.2014, at 07:39, Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> 
wrote:

> Although it's optional IBM POWER cpus always had DAR value set on
> alignment interrupt. So don't try to compute these values.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
> ---
> Changes from V2:
> * Depend on cpu feature flag to decide whether to use fault_dsir or not
> 
> arch/powerpc/include/asm/cputable.h    |  1 +
> arch/powerpc/include/asm/disassemble.h | 34 +++++++++++++++++
> arch/powerpc/kernel/align.c            | 34 +----------------
> arch/powerpc/kernel/cputable.c         | 15 +++++++-
> arch/powerpc/kvm/book3s_emulate.c      | 69 ++++++++++++++++------------------
> 5 files changed, 82 insertions(+), 71 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/cputable.h 
> b/arch/powerpc/include/asm/cputable.h
> index 0d4939ba48e7..1922dce6124d 100644
> --- a/arch/powerpc/include/asm/cputable.h
> +++ b/arch/powerpc/include/asm/cputable.h
> @@ -555,6 +555,7 @@ static inline int cpu_has_feature(unsigned long feature)
> }
> 
> #define HBP_NUM 1
> +extern struct cpu_spec *find_cpuspec(unsigned int pvr);
> 
> #endif /* !__ASSEMBLY__ */
> 
> diff --git a/arch/powerpc/include/asm/disassemble.h 
> b/arch/powerpc/include/asm/disassemble.h
> index 856f8deb557a..6330a61b875a 100644
> --- a/arch/powerpc/include/asm/disassemble.h
> +++ b/arch/powerpc/include/asm/disassemble.h
> @@ -81,4 +81,38 @@ static inline unsigned int get_oc(u32 inst)
> {
>       return (inst >> 11) & 0x7fff;
> }
> +
> +#define IS_XFORM(inst)       (get_op(inst)  == 31)
> +#define IS_DSFORM(inst)      (get_op(inst) >= 56)
> +
> +/*
> + * Create a DSISR value from the instruction
> + */
> +static inline unsigned make_dsisr(unsigned instr)
> +{
> +     unsigned dsisr;
> +
> +
> +     /* bits  6:15 --> 22:31 */
> +     dsisr = (instr & 0x03ff0000) >> 16;
> +
> +     if (IS_XFORM(instr)) {
> +             /* bits 29:30 --> 15:16 */
> +             dsisr |= (instr & 0x00000006) << 14;
> +             /* bit     25 -->    17 */
> +             dsisr |= (instr & 0x00000040) << 8;
> +             /* bits 21:24 --> 18:21 */
> +             dsisr |= (instr & 0x00000780) << 3;
> +     } else {
> +             /* bit      5 -->    17 */
> +             dsisr |= (instr & 0x04000000) >> 12;
> +             /* bits  1: 4 --> 18:21 */
> +             dsisr |= (instr & 0x78000000) >> 17;
> +             /* bits 30:31 --> 12:13 */
> +             if (IS_DSFORM(instr))
> +                     dsisr |= (instr & 0x00000003) << 18;
> +     }
> +
> +     return dsisr;
> +}
> #endif /* __ASM_PPC_DISASSEMBLE_H__ */
> diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
> index de91f3ae631e..111d93ec7f34 100644
> --- a/arch/powerpc/kernel/align.c
> +++ b/arch/powerpc/kernel/align.c
> @@ -25,14 +25,13 @@
> #include <asm/cputable.h>
> #include <asm/emulated_ops.h>
> #include <asm/switch_to.h>
> +#include <asm/disassemble.h>
> 
> struct aligninfo {
>       unsigned char len;
>       unsigned char flags;
> };
> 
> -#define IS_XFORM(inst)       (((inst) >> 26) == 31)
> -#define IS_DSFORM(inst)      (((inst) >> 26) >= 56)
> 
> #define INVALID       { 0, 0 }
> 
> @@ -192,37 +191,6 @@ static struct aligninfo aligninfo[128] = {
> };
> 
> /*
> - * Create a DSISR value from the instruction
> - */
> -static inline unsigned make_dsisr(unsigned instr)
> -{
> -     unsigned dsisr;
> -
> -
> -     /* bits  6:15 --> 22:31 */
> -     dsisr = (instr & 0x03ff0000) >> 16;
> -
> -     if (IS_XFORM(instr)) {
> -             /* bits 29:30 --> 15:16 */
> -             dsisr |= (instr & 0x00000006) << 14;
> -             /* bit     25 -->    17 */
> -             dsisr |= (instr & 0x00000040) << 8;
> -             /* bits 21:24 --> 18:21 */
> -             dsisr |= (instr & 0x00000780) << 3;
> -     } else {
> -             /* bit      5 -->    17 */
> -             dsisr |= (instr & 0x04000000) >> 12;
> -             /* bits  1: 4 --> 18:21 */
> -             dsisr |= (instr & 0x78000000) >> 17;
> -             /* bits 30:31 --> 12:13 */
> -             if (IS_DSFORM(instr))
> -                     dsisr |= (instr & 0x00000003) << 18;
> -     }
> -
> -     return dsisr;
> -}
> -
> -/*
>  * The dcbz (data cache block zero) instruction
>  * gives an alignment fault if used on non-cacheable
>  * memory.  We handle the fault mainly for the
> diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
> index 597d954e5860..b367f5b772f6 100644
> --- a/arch/powerpc/kernel/cputable.c
> +++ b/arch/powerpc/kernel/cputable.c
> @@ -116,7 +116,7 @@ extern void __restore_cpu_e6500(void);
>                                PPC_FEATURE_BOOKE)
> #endif
> 
> -static struct cpu_spec __initdata cpu_specs[] = {
> +static struct cpu_spec cpu_specs[] = {
> #ifdef CONFIG_PPC_BOOK3S_64
>       {       /* Power3 */
>               .pvr_mask               = 0xffff0000,
> @@ -2258,3 +2258,16 @@ struct cpu_spec * __init identify_cpu(unsigned long 
> offset, unsigned int pvr)
> 
>       return NULL;
> }
> +
> +struct cpu_spec *find_cpuspec(unsigned int pvr)
> +{
> +     int i;
> +     struct cpu_spec *s = cpu_specs;
> +
> +     for (i = 0; i < ARRAY_SIZE(cpu_specs); i++, s++) {
> +             if ((pvr & s->pvr_mask) == s->pvr_value)
> +                     return s;
> +     }
> +     return NULL;
> +}
> +EXPORT_SYMBOL_GPL(find_cpuspec);
> diff --git a/arch/powerpc/kvm/book3s_emulate.c 
> b/arch/powerpc/kvm/book3s_emulate.c
> index 99d40f8977e8..a7d54aa203d0 100644
> --- a/arch/powerpc/kvm/book3s_emulate.c
> +++ b/arch/powerpc/kvm/book3s_emulate.c
> @@ -569,48 +569,42 @@ unprivileged:
> 
> u32 kvmppc_alignment_dsisr(struct kvm_vcpu *vcpu, unsigned int inst)
> {
> -     u32 dsisr = 0;
> -
> -     /*
> -      * This is what the spec says about DSISR bits (not mentioned = 0):
> -      *
> -      * 12:13                [DS]    Set to bits 30:31
> -      * 15:16                [X]     Set to bits 29:30
> -      * 17                   [X]     Set to bit 25
> -      *                      [D/DS]  Set to bit 5
> -      * 18:21                [X]     Set to bits 21:24
> -      *                      [D/DS]  Set to bits 1:4
> -      * 22:26                        Set to bits 6:10 (RT/RS/FRT/FRS)
> -      * 27:31                        Set to bits 11:15 (RA)
> -      */
> -
> -     switch (get_op(inst)) {
> -     /* D-form */
> -     case OP_LFS:
> -     case OP_LFD:
> -     case OP_STFD:
> -     case OP_STFS:
> -             dsisr |= (inst >> 12) & 0x4000; /* bit 17 */
> -             dsisr |= (inst >> 17) & 0x3c00; /* bits 18:21 */
> -             break;
> -     /* X-form */
> -     case 31:
> -             dsisr |= (inst << 14) & 0x18000; /* bits 15:16 */
> -             dsisr |= (inst << 8)  & 0x04000; /* bit 17 */
> -             dsisr |= (inst << 3)  & 0x03c00; /* bits 18:21 */
> -             break;
> -     default:
> -             printk(KERN_INFO "KVM: Unaligned instruction 0x%x\n", inst);
> -             break;
> +     struct cpu_spec *s = find_cpuspec(vcpu->arch.pvr);

What if we don't find the pvr?

> +
> +     if (s->cpu_features & CPU_FTR_NODSISRALIGN) {
> +             /*
> +              * We don't care much we pass the DSISR we found on fault

Please indicate that this if() checks the guest cpu, while the other if() 
checks the host cpu.

> +              */
> +             return vcpu->arch.fault_dsisr;
> +     } else if (cpu_has_feature(CPU_FTR_NODSISRALIGN)) {
> +             /*
> +              * Fault DSISR is not valid, and virualized cpu expect a

virtualized

> +              * proper DSISR, so build one
> +              *
> +              * Mac OS X has some applications - namely the Finder - that
> +              * require alignment interrupts to work properly. So we need
> +              * to implement them.
> +              *
> +              * But the spec for 970 and 750 also looks different. While 750
> +              * requires the DSISR and DAR fields to reflect some instruction
> +              * bits (DSISR) and the fault address (DAR), the 970 declares
> +              * this as an optional feature. So we need to reconstruct DSISR
> +              * and DAR manually.
> +              */
> +             return make_dsisr(inst);

I quite frankly don't see why we're jumping through so many hoops here. Why 
doesn't dsisr reconstruction work in LE mode? And why do we care if the guest 
isn't guaranteed a working dsisr value?


Alex

> +     } else {
> +             /*
> +              * We have valid dsisr on fault
> +              */
> +             return vcpu->arch.fault_dsisr;
>       }
> -
> -     dsisr |= (inst >> 16) & 0x03ff; /* bits 22:31 */
> -
> -     return dsisr;
> }
> 
> ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, unsigned int inst)
> {
> +#ifdef CONFIG_PPC_BOOK3S_64
> +     return vcpu->arch.fault_dar;
> +#else
>       ulong dar = 0;
>       ulong ra = get_ra(inst);
>       ulong rb = get_rb(inst);
> @@ -635,4 +629,5 @@ ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, 
> unsigned int inst)
>       }
> 
>       return dar;
> +#endif
> }
> -- 
> 1.8.5.3
> 
> --
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