| Message ID | 70ede0d8bdcb14ea676c87f14a26788890a3ba4d.1494585671.git.ego@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 22c6663dc69a042a7b4158f162582b4b1ba7a4b7 |
| Headers | show |
On Tue, 16 May 2017 14:19:47 +0530 "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> wrote: > From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> > > On Power9 DD1 due to a hardware bug the Power-Saving Level Status > field (PLS) of the PSSCR for a thread waking up from a deep state can > under-report if some other thread in the core is in a shallow stop > state. The scenario in which this can manifest is as follows: > > 1) All the threads of the core are in deep stop. > 2) One of the threads is woken up. The PLS for this thread will > correctly reflect that it is waking up from deep stop. > 3) The thread that has woken up now executes a shallow stop. > 4) When some other thread in the core is woken, its PLS will reflect > the shallow stop state. > > Thus, the subsequent thread for which the PLS is under-reporting the > wakeup state will not restore the hypervisor resources. > > Hence, on DD1 systems, use the Requested Level (RL) field as a > workaround to restore the contents of the hypervisor resources on the > wakeup from the stop state. > > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Reviewed-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/include/asm/paca.h | 2 ++ > arch/powerpc/kernel/asm-offsets.c | 1 + > arch/powerpc/kernel/idle_book3s.S | 13 ++++++++++++- > 3 files changed, 15 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h > index 1c09f8f..77f60a0 100644 > --- a/arch/powerpc/include/asm/paca.h > +++ b/arch/powerpc/include/asm/paca.h > @@ -177,6 +177,8 @@ struct paca_struct { > * to the sibling threads' paca. > */ > struct paca_struct **thread_sibling_pacas; > + /* The PSSCR value that the kernel requested before going to stop */ > + u64 requested_psscr; > #endif > > #ifdef CONFIG_PPC_STD_MMU_64 > diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c > index 709e234..e15c178 100644 > --- a/arch/powerpc/kernel/asm-offsets.c > +++ b/arch/powerpc/kernel/asm-offsets.c > @@ -742,6 +742,7 @@ int main(void) > OFFSET(PACA_THREAD_MASK, paca_struct, thread_mask); > OFFSET(PACA_SUBCORE_SIBLING_MASK, paca_struct, subcore_sibling_mask); > OFFSET(PACA_SIBLING_PACA_PTRS, paca_struct, thread_sibling_pacas); > + OFFSET(PACA_REQ_PSSCR, paca_struct, requested_psscr); > #endif > > DEFINE(PPC_DBELL_SERVER, PPC_DBELL_SERVER); > diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S > index 6c9920d..98a6d07 100644 > --- a/arch/powerpc/kernel/idle_book3s.S > +++ b/arch/powerpc/kernel/idle_book3s.S > @@ -379,6 +379,7 @@ _GLOBAL(power9_idle_stop) > mfspr r5,SPRN_PSSCR > andc r5,r5,r4 > or r3,r3,r5 > + std r3, PACA_REQ_PSSCR(r13) > mtspr SPRN_PSSCR,r3 > LOAD_REG_ADDR(r5,power_enter_stop) > li r4,1 > @@ -498,12 +499,22 @@ pnv_restore_hyp_resource_arch300: > LOAD_REG_ADDRBASE(r5,pnv_first_deep_stop_state) > ld r4,ADDROFF(pnv_first_deep_stop_state)(r5) > > - mfspr r5,SPRN_PSSCR > +BEGIN_FTR_SECTION_NESTED(71) > + /* > + * Assume that we are waking up from the state > + * same as the Requested Level (RL) in the PSSCR > + * which are Bits 60-63 > + */ > + ld r5,PACA_REQ_PSSCR(r13) > + rldicl r5,r5,0,60 > +FTR_SECTION_ELSE_NESTED(71) > /* > * 0-3 bits correspond to Power-Saving Level Status > * which indicates the idle state we are waking up from > */ > + mfspr r5, SPRN_PSSCR > rldicl r5,r5,4,60 > +ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_POWER9_DD1, 71) > cmpd cr4,r5,r4 > bge cr4,pnv_wakeup_tb_loss /* returns to caller */ >
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h index 1c09f8f..77f60a0 100644 --- a/arch/powerpc/include/asm/paca.h +++ b/arch/powerpc/include/asm/paca.h @@ -177,6 +177,8 @@ struct paca_struct { * to the sibling threads' paca. */ struct paca_struct **thread_sibling_pacas; + /* The PSSCR value that the kernel requested before going to stop */ + u64 requested_psscr; #endif #ifdef CONFIG_PPC_STD_MMU_64 diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 709e234..e15c178 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -742,6 +742,7 @@ int main(void) OFFSET(PACA_THREAD_MASK, paca_struct, thread_mask); OFFSET(PACA_SUBCORE_SIBLING_MASK, paca_struct, subcore_sibling_mask); OFFSET(PACA_SIBLING_PACA_PTRS, paca_struct, thread_sibling_pacas); + OFFSET(PACA_REQ_PSSCR, paca_struct, requested_psscr); #endif DEFINE(PPC_DBELL_SERVER, PPC_DBELL_SERVER); diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index 6c9920d..98a6d07 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -379,6 +379,7 @@ _GLOBAL(power9_idle_stop) mfspr r5,SPRN_PSSCR andc r5,r5,r4 or r3,r3,r5 + std r3, PACA_REQ_PSSCR(r13) mtspr SPRN_PSSCR,r3 LOAD_REG_ADDR(r5,power_enter_stop) li r4,1 @@ -498,12 +499,22 @@ pnv_restore_hyp_resource_arch300: LOAD_REG_ADDRBASE(r5,pnv_first_deep_stop_state) ld r4,ADDROFF(pnv_first_deep_stop_state)(r5) - mfspr r5,SPRN_PSSCR +BEGIN_FTR_SECTION_NESTED(71) + /* + * Assume that we are waking up from the state + * same as the Requested Level (RL) in the PSSCR + * which are Bits 60-63 + */ + ld r5,PACA_REQ_PSSCR(r13) + rldicl r5,r5,0,60 +FTR_SECTION_ELSE_NESTED(71) /* * 0-3 bits correspond to Power-Saving Level Status * which indicates the idle state we are waking up from */ + mfspr r5, SPRN_PSSCR rldicl r5,r5,4,60 +ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_POWER9_DD1, 71) cmpd cr4,r5,r4 bge cr4,pnv_wakeup_tb_loss /* returns to caller */