@@ -216,6 +216,7 @@ enum {
#define CPU_FTR_PMAO_BUG LONG_ASM_CONST(0x1000000000000000)
#define CPU_FTR_SUBCORE LONG_ASM_CONST(0x2000000000000000)
#define CPU_FTR_POWER9_DD1 LONG_ASM_CONST(0x4000000000000000)
+#define CPU_FTR_LARGE_DEC LONG_ASM_CONST(0x8000000000000000)
#ifndef __ASSEMBLY__
@@ -496,7 +497,8 @@ enum {
(CPU_FTRS_POWER4 | CPU_FTRS_PPC970 | CPU_FTRS_POWER5 | \
CPU_FTRS_POWER6 | CPU_FTRS_POWER7 | CPU_FTRS_POWER8E | \
CPU_FTRS_POWER8 | CPU_FTRS_POWER8_DD1 | CPU_FTRS_CELL | \
- CPU_FTRS_PA6T | CPU_FTR_VSX | CPU_FTRS_POWER9 | CPU_FTRS_POWER9_DD1)
+ CPU_FTRS_PA6T | CPU_FTR_VSX | CPU_FTRS_POWER9 | \
+ CPU_FTRS_POWER9_DD1 | CPU_FTR_LARGE_DEC)
#endif
#else
enum {
@@ -259,6 +259,7 @@ static struct feature_property {
{"ibm,dfp", 1, 0, PPC_FEATURE_HAS_DFP},
{"ibm,purr", 1, CPU_FTR_PURR, 0},
{"ibm,spurr", 1, CPU_FTR_SPURR, 0},
+ {"ibm,dec-bits", 32, CPU_FTR_LARGE_DEC, 0},
#endif /* CONFIG_PPC64 */
};
@@ -946,10 +946,7 @@ static void register_decrementer_clockevent(int cpu)
static void enable_large_decrementer(void)
{
- if (!cpu_has_feature(CPU_FTR_ARCH_300))
- return;
-
- if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
+ if (!cpu_has_feature(CPU_FTR_LARGE_DEC))
return;
/*
@@ -966,7 +963,7 @@ static void __init set_decrementer_max(void)
u32 bits = 32;
/* Prior to ISAv3 the decrementer is always 32 bit */
- if (!cpu_has_feature(CPU_FTR_ARCH_300))
+ if (!cpu_has_feature(CPU_FTR_LARGE_DEC))
return;
cpu = of_find_node_by_type(NULL, "cpu");
@@ -124,7 +124,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
mfspr r8,SPRN_DEC
mftb r7
mtspr SPRN_HDEC,r8
+BEGIN_FTR_SECTION
extsw r8,r8
+END_FTR_SECTION_IFCLR(CPU_FTR_LARGE_DEC)
add r8,r8,r7
std r8,HSTATE_DECEXP(r13)
@@ -214,6 +214,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
kvmppc_primary_no_guest:
/* We handle this much like a ceded vcpu */
/* put the HDEC into the DEC, since HDEC interrupts don't wake us */
+ /* HDEC may be larger than DEC for arch >= v3.00, but since the */
+ /* HDEC value came from DEC in the first place, it will fit */
mfspr r3, SPRN_HDEC
mtspr SPRN_DEC, r3
/*
@@ -295,8 +297,11 @@ kvm_novcpu_wakeup:
/* See if our timeslice has expired (HDEC is negative) */
mfspr r0, SPRN_HDEC
+BEGIN_FTR_SECTION
+ extsw r0, r0
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
li r12, BOOK3S_INTERRUPT_HV_DECREMENTER
- cmpwi r0, 0
+ cmpdi r0, 0
blt kvm_novcpu_exit
/* Got an IPI but other vcpus aren't yet exiting, must be a latecomer */
@@ -390,8 +395,8 @@ kvm_secondary_got_guest:
lbz r4, HSTATE_PTID(r13)
cmpwi r4, 0
bne 63f
- lis r6, 0x7fff
- ori r6, r6, 0xffff
+ LOAD_REG_ADDR(r6, decrementer_max)
+ ld r6, 0(r6)
mtspr SPRN_HDEC, r6
/* and set per-LPAR registers, if doing dynamic micro-threading */
ld r6, HSTATE_SPLIT_MODE(r13)
@@ -968,7 +973,10 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300)
/* Check if HDEC expires soon */
mfspr r3, SPRN_HDEC
- cmpwi r3, 512 /* 1 microsecond */
+BEGIN_FTR_SECTION
+ extsw r3, r3
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
+ cmpdi r3, 512 /* 1 microsecond */
blt hdec_soon
#ifdef CONFIG_KVM_XICS
@@ -2366,12 +2374,15 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
mfspr r3, SPRN_DEC
mfspr r4, SPRN_HDEC
mftb r5
- cmpw r3, r4
+ extsw r3, r3
+BEGIN_FTR_SECTION
+ extsw r4, r4
+END_FTR_SECTION_IFSET(CPU_FTR_LARGE_DEC)
+ cmpd r3, r4
ble 67f
mtspr SPRN_DEC, r4
67:
/* save expiry time of guest decrementer */
- extsw r3, r3
add r3, r3, r5
ld r4, HSTATE_KVM_VCPU(r13)
ld r5, HSTATE_KVM_VCORE(r13)
POWER9 introduces a new mode for the decrementer register, called large decrementer mode, in which the decrementer counter is 56 bits wide rather than 32, and reads are sign-extended rather than zero-extended. Since KVM code reads and writes the host decrementer value in a few places, it needs to be aware of the need to treat the decrementer value as a 64-bit quantity, and only do a 32-bit sign extension when large decrementer mode is not in effect. To enable the sign extension to be removed in large decrementer mode, we use a CPU feature bit to indicate that large decrementer mode is in effect. This CPU feature bit is derived from the presence of the ibm,dec-bits property in the cpu nodes of the firmware device tree. This property is already set by firmware in the device tree that the kernel uses when running as a host. We change the kernel timer code to use this bit and enable large decrementer mode whenever it is set (even if firmware tells us that the large decrementer mode only gives us 32 bits) so that we get the sign extension in hardware. This is partly based on an earlier patch by Oliver O'Halloran. Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Paul Mackerras <paulus@ozlabs.org> --- arch/powerpc/include/asm/cputable.h | 4 +++- arch/powerpc/kernel/prom.c | 1 + arch/powerpc/kernel/time.c | 7 ++----- arch/powerpc/kvm/book3s_hv_interrupts.S | 2 ++ arch/powerpc/kvm/book3s_hv_rmhandlers.S | 23 +++++++++++++++++------ 5 files changed, 25 insertions(+), 12 deletions(-)