[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v2 4/4] x86/APIC: make connections between seemingly arbitrary numbers
Making adjustments to arbitrarily chosen values shouldn't require auditing the code for possible derived numbers - such a change should be doable in a single place, having an effect on all code depending on that choice. For one make the TDCR write actually use APIC_DIVISOR. With the necessary mask constant introduced, also use that in vLAPIC code. While introducing the constant, drop APIC_TDR_DIV_TMBASE: The bit has been undefined in halfway recent SDM and PM versions. And then introduce a constant tying together the scale used when converting nanoseconds to bus clocks. No functional change intended. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- I thought we have a generic "glue" macro, but I couldn't find one. Hence I'm (ab)using _AC(). --- v2: New. --- a/xen/arch/x86/apic.c +++ b/xen/arch/x86/apic.c @@ -1078,8 +1078,8 @@ static void __setup_APIC_LVTT(unsigned i lvtt_value = /*APIC_TIMER_MODE_PERIODIC |*/ LOCAL_TIMER_VECTOR; apic_write(APIC_LVTT, lvtt_value); - tmp_value = apic_read(APIC_TDCR); - apic_write(APIC_TDCR, tmp_value | APIC_TDR_DIV_1); + tmp_value = apic_read(APIC_TDCR) & ~APIC_TDR_DIV_MASK; + apic_write(APIC_TDCR, tmp_value | _AC(APIC_TDR_DIV_, APIC_DIVISOR)); apic_write(APIC_TMICT, clocks / APIC_DIVISOR); } @@ -1196,6 +1196,8 @@ static void __init check_deadline_errata * APIC irq that way. */ +#define BUS_SCALE_SHIFT 18 + static void __init calibrate_APIC_clock(void) { unsigned long bus_freq; /* KAF: pointer-size avoids compile warns. */ @@ -1249,8 +1251,8 @@ static void __init calibrate_APIC_clock( /* set up multipliers for accurate timer code */ bus_cycle = 1000000000000UL / bus_freq; /* in pico seconds */ bus_cycle += (1000000000000UL % bus_freq) * 2 > bus_freq; - bus_scale = (1000*262144)/bus_cycle; - bus_scale += ((1000 * 262144) % bus_cycle) * 2 > bus_cycle; + bus_scale = (1000 << BUS_SCALE_SHIFT) / bus_cycle; + bus_scale += ((1000 << BUS_SCALE_SHIFT) % bus_cycle) * 2 > bus_cycle; apic_printk(APIC_VERBOSE, "..... bus_scale = %#x\n", bus_scale); /* reset APIC to zero timeout value */ @@ -1337,7 +1339,8 @@ int reprogram_timer(s_time_t timeout) } if ( timeout && ((expire = timeout - NOW()) > 0) ) - apic_tmict = min_t(u64, (bus_scale * expire) >> 18, UINT_MAX); + apic_tmict = min_t(uint64_t, (bus_scale * expire) >> BUS_SCALE_SHIFT, + UINT32_MAX); apic_write(APIC_TMICT, (unsigned long)apic_tmict); --- a/xen/arch/x86/hvm/vlapic.c +++ b/xen/arch/x86/hvm/vlapic.c @@ -580,7 +580,7 @@ static uint32_t vlapic_get_tmcct(const s static void vlapic_set_tdcr(struct vlapic *vlapic, unsigned int val) { /* Only bits 0, 1 and 3 are settable; others are MBZ. */ - val &= 0xb; + val &= APIC_TDR_DIV_MASK; vlapic_set_reg(vlapic, APIC_TDCR, val); /* Update the demangled hw.timer_divisor. */ @@ -887,7 +887,7 @@ void vlapic_reg_write(struct vcpu *v, un { uint32_t current_divisor = vlapic->hw.timer_divisor; - vlapic_set_tdcr(vlapic, val & 0xb); + vlapic_set_tdcr(vlapic, val); vlapic_update_timer(vlapic, vlapic_get_reg(vlapic, APIC_LVTT), false, current_divisor); @@ -1019,7 +1019,7 @@ int guest_wrmsr_x2apic(struct vcpu *v, u break; case APIC_TDCR: - if ( msr_content & ~APIC_TDR_DIV_1 ) + if ( msr_content & ~APIC_TDR_DIV_MASK ) return X86EMUL_EXCEPTION; break; --- a/xen/arch/x86/include/asm/apicdef.h +++ b/xen/arch/x86/include/asm/apicdef.h @@ -106,7 +106,7 @@ #define APIC_TMICT 0x380 #define APIC_TMCCT 0x390 #define APIC_TDCR 0x3E0 -#define APIC_TDR_DIV_TMBASE (1<<2) +#define APIC_TDR_DIV_MASK 0xB #define APIC_TDR_DIV_1 0xB #define APIC_TDR_DIV_2 0x0 #define APIC_TDR_DIV_4 0x1
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