mirror of https://gitee.com/openkylin/linux.git
KVM: PPC: Book3S HV: Use stop instruction rather than nap on POWER9
POWER9 replaces the various power-saving mode instructions on POWER8 (doze, nap, sleep and rvwinkle) with a single "stop" instruction, plus a register, PSSCR, which controls the depth of the power-saving mode. This replaces the use of the nap instruction when threads are idle during guest execution with the stop instruction, and adds code to set PSSCR to a value which will allow an SMT mode switch while the thread is idle (given that the core as a whole won't be idle in these cases). Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
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@ -501,17 +501,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
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cmpwi r0, 0
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beq 57f
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li r3, (LPCR_PECEDH | LPCR_PECE0) >> 4
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mfspr r4, SPRN_LPCR
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rlwimi r4, r3, 4, (LPCR_PECEDP | LPCR_PECEDH | LPCR_PECE0 | LPCR_PECE1)
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mtspr SPRN_LPCR, r4
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isync
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std r0, HSTATE_SCRATCH0(r13)
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ptesync
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ld r0, HSTATE_SCRATCH0(r13)
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1: cmpd r0, r0
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bne 1b
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nap
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b .
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mfspr r5, SPRN_LPCR
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rlwimi r5, r3, 4, (LPCR_PECEDP | LPCR_PECEDH | LPCR_PECE0 | LPCR_PECE1)
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b kvm_nap_sequence
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57: li r0, 0
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stbx r0, r3, r4
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@ -2256,6 +2248,21 @@ BEGIN_FTR_SECTION
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ori r5, r5, LPCR_PECEDH
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rlwimi r5, r3, 0, LPCR_PECEDP
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END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
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kvm_nap_sequence: /* desired LPCR value in r5 */
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BEGIN_FTR_SECTION
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/*
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* PSSCR bits: exit criterion = 1 (wakeup based on LPCR at sreset)
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* enable state loss = 1 (allow SMT mode switch)
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* requested level = 0 (just stop dispatching)
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*/
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lis r3, (PSSCR_EC | PSSCR_ESL)@h
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mtspr SPRN_PSSCR, r3
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/* Set LPCR_PECE_HVEE bit to enable wakeup by HV interrupts */
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li r4, LPCR_PECE_HVEE@higher
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sldi r4, r4, 32
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or r5, r5, r4
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END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
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mtspr SPRN_LPCR,r5
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isync
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li r0, 0
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@ -2264,7 +2271,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
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ld r0, HSTATE_SCRATCH0(r13)
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1: cmpd r0, r0
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bne 1b
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BEGIN_FTR_SECTION
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nap
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FTR_SECTION_ELSE
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PPC_STOP
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ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
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b .
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33: mr r4, r3
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