On 07.07.2012, at 10:39, Caraman Mihai Claudiu-B02008 wrote: >> ________________________________________ >> From: Alexander Graf [agraf@xxxxxxx] >> Sent: Saturday, July 07, 2012 2:11 AM >> To: Caraman Mihai Claudiu-B02008 >> Cc: Benjamin Herrenschmidt; <kvm-ppc@xxxxxxxxxxxxxxx>; KVM list; linuxppc-dev; qemu-ppc@xxxxxxxxxx List >> Subject: Re: [Qemu-ppc] [RFC PATCH 12/17] PowerPC: booke64: Add DO_KVM kernel hooks >> >> On 07.07.2012, at 00:33, Caraman Mihai Claudiu-B02008 wrote: >> >>>> -----Original Message----- >>>> From: Benjamin Herrenschmidt [mailto:benh@xxxxxxxxxxxxxxxxxxx] >>>> Sent: Thursday, July 05, 2012 1:26 AM >>>> To: Alexander Graf >>>> Cc: Caraman Mihai Claudiu-B02008; <kvm-ppc@xxxxxxxxxxxxxxx>; KVM list; >>>> linuxppc-dev; qemu-ppc@xxxxxxxxxx List >>>> Subject: Re: [Qemu-ppc] [RFC PATCH 12/17] PowerPC: booke64: Add DO_KVM >>>> kernel hooks >>>> >>>> You can't but in any case I don't see the point of the conditional here, >>>> we'll eventually have to load srr1 no ? We can move the load up to here >>>> in all cases or can't we ? >>> >>> I like the idea, but there is a problem with addition macros which may clobber >>> r11 and PROLOG_ADDITION_MASKABLE_GEN is such a case. >> >> Mike -v please :) > > Ben suggested something like this: > > #define EXCEPTION_PROLOG(n, type, addition) \ > mtspr SPRN_SPRG_##type##_SCRATCH,r13; /* get spare registers */ \ > mfspr r13,SPRN_SPRG_PACA; /* get PACA */ \ > std r10,PACA_EX##type+EX_R10(r13); \ > std r11,PACA_EX##type+EX_R11(r13); \ > mfcr r10; /* save CR */ \ > + mfspr r11,SPRN_##type##_SRR1;/* what are we coming from */ \ > DO_KVM intnum,srr1; \ > addition; /* additional code for that exc. */ \ > std r1,PACA_EX##type+EX_R1(r13); /* save old r1 in the PACA */ \ > stw r10,PACA_EX##type+EX_CR(r13); /* save old CR in the PACA */ \ > - mfspr r11,SPRN_##type##_SRR1;/* what are we coming from */ \ > type##_SET_KSTACK; /* get special stack if necessary */\ > andi. r10,r11,MSR_PR; /* save stack pointer */ \ > > But one of the addition looks like this: > > #define PROLOG_ADDITION_MASKABLE_GEN(n) \ > lbz r11,PACASOFTIRQEN(r13); /* are irqs soft-disabled ? */ \ > cmpwi cr0,r11,0; /* yes -> go out of line */ \ > beq masked_interrupt_book3e_##n > > So for maskable gen we end up with: > > #define EXCEPTION_PROLOG(n, type, addition) \ > mtspr SPRN_SPRG_##type##_SCRATCH,r13; /* get spare registers */ \ > mfspr r13,SPRN_SPRG_PACA; /* get PACA */ \ > std r10,PACA_EX##type+EX_R10(r13); \ > std r11,PACA_EX##type+EX_R11(r13); \ > mfcr r10; /* save CR */ \ > mfspr r11,SPRN_##type##_SRR1;/* what are we coming from */ \ > DO_KVM intnum,srr1; \ > lbz r11,PACASOFTIRQEN(r13); /* are irqs soft-disabled ? */ \ > cmpwi cr0,r11,0; /* yes -> go out of line */ \ > beq masked_interrupt_book3e_##n \ > std r1,PACA_EX##type+EX_R1(r13); /* save old r1 in the PACA */ \ > stw r10,PACA_EX##type+EX_CR(r13); /* save old CR in the PACA */ \ > type##_SET_KSTACK; /* get special stack if necessary */\ > andi. r10,r11,MSR_PR; /* save stack pointer */ \ > > This affects the last asm line, we load srr1 into r11 but clobber it in-between. > We need a spare register for maskable gen addition. I think we can free r10 sooner > and used it in addition like this: Ah, makes sense, yes. > > #define EXCEPTION_PROLOG(n, type, addition) \ > mtspr SPRN_SPRG_##type##_SCRATCH,r13; /* get spare registers */ \ > mfspr r13,SPRN_SPRG_PACA; /* get PACA */ \ > std r10,PACA_EX##type+EX_R10(r13); \ > std r11,PACA_EX##type+EX_R11(r13); \ Or just free up another register early on, like here. Alex > + mfspr r11,SPRN_##type##_SRR1;/* what are we coming from */ \ > mfcr r10; /* save CR */ \ > + stw r10,PACA_EX##type+EX_CR(r13); /* save old CR in the PACA */ \ > DO_KVM intnum,srr1; \ > - lbz r11,PACASOFTIRQEN(r13); /* are irqs soft-disabled ? */ \ > - cmpwi cr0,r11,0; /* yes -> go out of line */ \ > + lbz r10,PACASOFTIRQEN(r13); /* are irqs soft-disabled ? */ \ > + cmpwi cr0,r10,0; /* yes -> go out of line */ \ > beq masked_interrupt_book3e_##n \ > std r1,PACA_EX##type+EX_R1(r13); /* save old r1 in the PACA */ \ > - stw r10,PACA_EX##type+EX_CR(r13); /* save old CR in the PACA */ \ > - mfspr r11,SPRN_##type##_SRR1;/* what are we coming from */ \ > type##_SET_KSTACK; /* get special stack if necessary */\ > andi. r10,r11,MSR_PR; /* save stack pointer */ \ > > -Mike > -- > To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
