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Violators will be prosecuted for from ; Thu, 16 Mar 2017 09:19:13 -0400 Date: Thu, 16 Mar 2017 18:49:07 +0530 From: Gautham R Shenoy To: Nicholas Piggin Cc: Mahesh Jagannath Salgaonkar , linuxppc-dev@lists.ozlabs.org, Gautham R Shenoy Subject: Re: [PATCH 4/8] powerpc/64s: fix POWER9 machine check handler from stop state Reply-To: ego@linux.vnet.ibm.com References: <20170314092349.10981-1-npiggin@gmail.com> <20170314092349.10981-5-npiggin@gmail.com> <67bd0a9f-ebaa-acdb-cfbf-8a4acba256a3@linux.vnet.ibm.com> <20170316230520.5ba5528e@roar.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20170316230520.5ba5528e@roar.ozlabs.ibm.com> Message-Id: <20170316131907.GF16462@in.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, On Thu, Mar 16, 2017 at 11:05:20PM +1000, Nicholas Piggin wrote: > On Thu, 16 Mar 2017 18:10:48 +0530 > Mahesh Jagannath Salgaonkar wrote: > > > On 03/14/2017 02:53 PM, Nicholas Piggin wrote: > > > The ISA specifies power save wakeup can cause a machine check interrupt. > > > The machine check handler currently has code to handle that for POWER8, > > > but POWER9 crashes when trying to execute the P8 style sleep > > > instructions. > > > > > > So queue up the machine check, then call into the idle code to wake up > > > as the system reset interrupt does, rather than attempting to sleep > > > again without going through the main idle path. > > > > > > Reviewed-by: Gautham R. Shenoy > > > Signed-off-by: Nicholas Piggin > > > --- > > > arch/powerpc/include/asm/reg.h | 1 + > > > arch/powerpc/kernel/exceptions-64s.S | 69 ++++++++++++++++++------------------ > > > 2 files changed, 35 insertions(+), 35 deletions(-) > > > > > > diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h > > > index fc879fd6bdae..8bbdfacce970 100644 > > > --- a/arch/powerpc/include/asm/reg.h > > > +++ b/arch/powerpc/include/asm/reg.h > > > @@ -656,6 +656,7 @@ > > > #define SRR1_ISI_PROT 0x08000000 /* ISI: Other protection fault */ > > > #define SRR1_WAKEMASK 0x00380000 /* reason for wakeup */ > > > #define SRR1_WAKEMASK_P8 0x003c0000 /* reason for wakeup on POWER8 and 9 */ > > > +#define SRR1_WAKEMCE_RESVD 0x003c0000 /* Unused/reserved value used by MCE wakeup to indicate cause to idle wakeup handler */ > > > #define SRR1_WAKESYSERR 0x00300000 /* System error */ > > > #define SRR1_WAKEEE 0x00200000 /* External interrupt */ > > > #define SRR1_WAKEHVI 0x00240000 /* Hypervisor Virtualization Interrupt (P9) */ > > > diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S > > > index e390fcd04bcb..5779d2d6a192 100644 > > > --- a/arch/powerpc/kernel/exceptions-64s.S > > > +++ b/arch/powerpc/kernel/exceptions-64s.S > > > @@ -306,6 +306,33 @@ EXC_COMMON_BEGIN(machine_check_common) > > > /* restore original r1. */ \ > > > ld r1,GPR1(r1) > > > > > > +#ifdef CONFIG_PPC_P7_NAP > > > +EXC_COMMON_BEGIN(machine_check_idle_common) > > > + bl machine_check_queue_event > > > + /* > > > + * Queue the machine check, then reload SRR1 and use it to set > > > + * CR3 according to pnv_powersave_wakeup convention. > > > + */ > > > + ld r12,_MSR(r1) > > > + rlwinm r11,r12,47-31,30,31 > > > + cmpwi cr3,r11,2 > > > + > > > + /* > > > + * Now put SRR1_WAKEMCE_RESVD into SRR1, allows it to follow the > > > + * system reset wakeup code. > > > + */ > > > + oris r12,r12,SRR1_WAKEMCE_RESVD@h > > > + mtspr SPRN_SRR1,r12 > > > + std r12,_MSR(r1) > > > + > > > + /* > > > + * Decrement MCE nesting after finishing with the stack. > > > + */ > > > + lhz r11,PACA_IN_MCE(r13) > > > + subi r11,r11,1 > > > + sth r11,PACA_IN_MCE(r13) > > > > Looks like we are not winding up.. Shouldn't we ? What if we may end up > > in pnv_wakeup_noloss() which assumes that no GPRs are lost. Am I missing > > anything ? Nice catch! This can occur if SRR1[46:47] == 0b01. > > Hmm, no I think you're right. Thanks, good catch. But can we do it with > just setting PACA_NAPSTATELOST? Unconditionally setting PACA_NAPSTATELOST should be sufficient. > > > > > > + b pnv_powersave_wakeup > > > +#endif > > > /* > > > > [...] > > > > Rest looks good to me. > > > > Reviewed-by: Mahesh J Salgaonkar > > Thanks, > Nick >