Patchwork [2/2] powerpc/e6500: TLB miss handler with hardware tablewalk support

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Submitter Caraman Mihai Claudiu-B02008
Date Sept. 11, 2012, 5:06 p.m.
Message ID <300B73AA675FCE4A93EB4FC1D42459FF1DC945@039-SN2MPN1-011.039d.mgd.msft.net>
Download mbox | patch
Permalink /patch/183157/
State Not Applicable
Headers show

Comments

Caraman Mihai Claudiu-B02008 - Sept. 11, 2012, 5:06 p.m.
> diff --git a/arch/powerpc/mm/tlb_low_64e.S
> b/arch/powerpc/mm/tlb_low_64e.S
> index efe0f33..8e82772 100644
> --- a/arch/powerpc/mm/tlb_low_64e.S
> +++ b/arch/powerpc/mm/tlb_low_64e.S
> @@ -232,6 +232,173 @@ itlb_miss_fault_bolted:
>  	beq	tlb_miss_common_bolted
>  	b	itlb_miss_kernel_bolted
> 
> +/*
> + * TLB miss handling for e6500 and derivatives, using hardware
> tablewalk.
> + *
> + * Linear mapping is bolted: no virtual page table or nested TLB misses
> + * Indirect entries in TLB1, hardware loads resulting direct entries
> + *    into TLB0
> + * No HES or NV hint on TLB1, so we need to do software round-robin
> + * No tlbsrx. so we need a spinlock, and we have to deal
> + *    with MAS-damage caused by tlbsx
> + * 4K pages only
> + */
> +
> +	START_EXCEPTION(instruction_tlb_miss_e6500)
> +	tlb_prolog_bolted SPRN_SRR0
> +
> +	ld	r11,PACA_TLB_PER_CORE_PTR(r13)
> +	srdi.	r15,r16,60		/* get region */
> +	ori	r16,r16,1
> +
> +	TLB_MISS_STATS_SAVE_INFO_BOLTED
> +	bne	tlb_miss_kernel_e6500	/* user/kernel test */
> +
> +	b	tlb_miss_common_e6500
> +
> +	START_EXCEPTION(data_tlb_miss_e6500)
> +	tlb_prolog_bolted SPRN_DEAR
> +
> +	ld	r11,PACA_TLB_PER_CORE_PTR(r13)
> +	srdi.	r15,r16,60		/* get region */
> +	rldicr	r16,r16,0,62
> +
> +	TLB_MISS_STATS_SAVE_INFO_BOLTED
> +	bne	tlb_miss_kernel_e6500	/* user vs kernel check */
> +

This ends up calling DO_KVM macro twice with same parameters which
generates the following compile error:

 arch/powerpc/mm/tlb_low_64e.S:307: Error: symbol `kvmppc_resume_14_0x01B' is already defined
 arch/powerpc/mm/tlb_low_64e.S:319: Error: symbol `kvmppc_resume_13_0x01B' is already defined

We can live with it if we patch DO_KVM like this:


-Mike
Scott Wood - Sept. 11, 2012, 5:24 p.m.
On 09/11/2012 12:06 PM, Caraman Mihai Claudiu-B02008 wrote:
>> diff --git a/arch/powerpc/mm/tlb_low_64e.S
>> b/arch/powerpc/mm/tlb_low_64e.S
>> index efe0f33..8e82772 100644
>> --- a/arch/powerpc/mm/tlb_low_64e.S
>> +++ b/arch/powerpc/mm/tlb_low_64e.S
>> @@ -232,6 +232,173 @@ itlb_miss_fault_bolted:
>>  	beq	tlb_miss_common_bolted
>>  	b	itlb_miss_kernel_bolted
>>
>> +/*
>> + * TLB miss handling for e6500 and derivatives, using hardware
>> tablewalk.
>> + *
>> + * Linear mapping is bolted: no virtual page table or nested TLB misses
>> + * Indirect entries in TLB1, hardware loads resulting direct entries
>> + *    into TLB0
>> + * No HES or NV hint on TLB1, so we need to do software round-robin
>> + * No tlbsrx. so we need a spinlock, and we have to deal
>> + *    with MAS-damage caused by tlbsx
>> + * 4K pages only
>> + */
>> +
>> +	START_EXCEPTION(instruction_tlb_miss_e6500)
>> +	tlb_prolog_bolted SPRN_SRR0
>> +
>> +	ld	r11,PACA_TLB_PER_CORE_PTR(r13)
>> +	srdi.	r15,r16,60		/* get region */
>> +	ori	r16,r16,1
>> +
>> +	TLB_MISS_STATS_SAVE_INFO_BOLTED
>> +	bne	tlb_miss_kernel_e6500	/* user/kernel test */
>> +
>> +	b	tlb_miss_common_e6500
>> +
>> +	START_EXCEPTION(data_tlb_miss_e6500)
>> +	tlb_prolog_bolted SPRN_DEAR
>> +
>> +	ld	r11,PACA_TLB_PER_CORE_PTR(r13)
>> +	srdi.	r15,r16,60		/* get region */
>> +	rldicr	r16,r16,0,62
>> +
>> +	TLB_MISS_STATS_SAVE_INFO_BOLTED
>> +	bne	tlb_miss_kernel_e6500	/* user vs kernel check */
>> +
> 
> This ends up calling DO_KVM macro twice with same parameters which
> generates the following compile error:
> 
>  arch/powerpc/mm/tlb_low_64e.S:307: Error: symbol `kvmppc_resume_14_0x01B' is already defined
>  arch/powerpc/mm/tlb_low_64e.S:319: Error: symbol `kvmppc_resume_13_0x01B' is already defined

I assume the reason you don't already see this is because you only did
DO_KVM for the bolted version of the handlers.

> We can live with it if we patch DO_KVM like this:
> 
> diff --git a/arch/powerpc/include/asm/kvm_booke_hv_asm.h b/arch/powerpc/include/asm/kvm_booke_hv_asm.h
> index 4610fb0..029ecab 100644
> --- a/arch/powerpc/include/asm/kvm_booke_hv_asm.h
> +++ b/arch/powerpc/include/asm/kvm_booke_hv_asm.h
> @@ -55,9 +55,9 @@
>  #ifdef CONFIG_KVM_BOOKE_HV
>  BEGIN_FTR_SECTION
>         mtocrf  0x80, r11       /* check MSR[GS] without clobbering reg */
> -       bf      3, kvmppc_resume_\intno\()_\srr1
> +       bf      3, 1f
>         b       kvmppc_handler_\intno\()_\srr1
> -kvmppc_resume_\intno\()_\srr1:
> +1:
>  END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
>  #endif
>  .endm

Please do that, though maybe use a more unique label number in case the
calling context is using numbered labels.

-Scott

Patch

diff --git a/arch/powerpc/include/asm/kvm_booke_hv_asm.h b/arch/powerpc/include/asm/kvm_booke_hv_asm.h
index 4610fb0..029ecab 100644
--- a/arch/powerpc/include/asm/kvm_booke_hv_asm.h
+++ b/arch/powerpc/include/asm/kvm_booke_hv_asm.h
@@ -55,9 +55,9 @@ 
 #ifdef CONFIG_KVM_BOOKE_HV
 BEGIN_FTR_SECTION
        mtocrf  0x80, r11       /* check MSR[GS] without clobbering reg */
-       bf      3, kvmppc_resume_\intno\()_\srr1
+       bf      3, 1f
        b       kvmppc_handler_\intno\()_\srr1
-kvmppc_resume_\intno\()_\srr1:
+1:
 END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
 #endif
 .endm