diff options
Diffstat (limited to 'arch/mips/kvm/kvm_mips_emul.c')
| -rw-r--r-- | arch/mips/kvm/kvm_mips_emul.c | 557 |
1 files changed, 532 insertions, 25 deletions
diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c index e3fec99941a7..8d4840090082 100644 --- a/arch/mips/kvm/kvm_mips_emul.c +++ b/arch/mips/kvm/kvm_mips_emul.c @@ -11,6 +11,7 @@ #include <linux/errno.h> #include <linux/err.h> +#include <linux/ktime.h> #include <linux/kvm_host.h> #include <linux/module.h> #include <linux/vmalloc.h> @@ -228,25 +229,520 @@ enum emulation_result update_pc(struct kvm_vcpu *vcpu, uint32_t cause) return er; } -/* Everytime the compare register is written to, we need to decide when to fire - * the timer that represents timer ticks to the GUEST. +/** + * kvm_mips_count_disabled() - Find whether the CP0_Count timer is disabled. + * @vcpu: Virtual CPU. * + * Returns: 1 if the CP0_Count timer is disabled by either the guest + * CP0_Cause.DC bit or the count_ctl.DC bit. + * 0 otherwise (in which case CP0_Count timer is running). */ -enum emulation_result kvm_mips_emulate_count(struct kvm_vcpu *vcpu) +static inline int kvm_mips_count_disabled(struct kvm_vcpu *vcpu) { struct mips_coproc *cop0 = vcpu->arch.cop0; - enum emulation_result er = EMULATE_DONE; + return (vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) || + (kvm_read_c0_guest_cause(cop0) & CAUSEF_DC); +} + +/** + * kvm_mips_ktime_to_count() - Scale ktime_t to a 32-bit count. + * + * Caches the dynamic nanosecond bias in vcpu->arch.count_dyn_bias. + * + * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is running). + */ +static uint32_t kvm_mips_ktime_to_count(struct kvm_vcpu *vcpu, ktime_t now) +{ + s64 now_ns, periods; + u64 delta; + + now_ns = ktime_to_ns(now); + delta = now_ns + vcpu->arch.count_dyn_bias; + + if (delta >= vcpu->arch.count_period) { + /* If delta is out of safe range the bias needs adjusting */ + periods = div64_s64(now_ns, vcpu->arch.count_period); + vcpu->arch.count_dyn_bias = -periods * vcpu->arch.count_period; + /* Recalculate delta with new bias */ + delta = now_ns + vcpu->arch.count_dyn_bias; + } + + /* + * We've ensured that: + * delta < count_period + * + * Therefore the intermediate delta*count_hz will never overflow since + * at the boundary condition: + * delta = count_period + * delta = NSEC_PER_SEC * 2^32 / count_hz + * delta * count_hz = NSEC_PER_SEC * 2^32 + */ + return div_u64(delta * vcpu->arch.count_hz, NSEC_PER_SEC); +} + +/** + * kvm_mips_count_time() - Get effective current time. + * @vcpu: Virtual CPU. + * + * Get effective monotonic ktime. This is usually a straightforward ktime_get(), + * except when the master disable bit is set in count_ctl, in which case it is + * count_resume, i.e. the time that the count was disabled. + * + * Returns: Effective monotonic ktime for CP0_Count. + */ +static inline ktime_t kvm_mips_count_time(struct kvm_vcpu *vcpu) +{ + if (unlikely(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC)) + return vcpu->arch.count_resume; + + return ktime_get(); +} + +/** + * kvm_mips_read_count_running() - Read the current count value as if running. + * @vcpu: Virtual CPU. + * @now: Kernel time to read CP0_Count at. + * + * Returns the current guest CP0_Count register at time @now and handles if the + * timer interrupt is pending and hasn't been handled yet. + * + * Returns: The current value of the guest CP0_Count register. + */ +static uint32_t kvm_mips_read_count_running(struct kvm_vcpu *vcpu, ktime_t now) +{ + ktime_t expires; + int running; + + /* Is the hrtimer pending? */ + expires = hrtimer_get_expires(&vcpu->arch.comparecount_timer); + if (ktime_compare(now, expires) >= 0) { + /* + * Cancel it while we handle it so there's no chance of + * interference with the timeout handler. + */ + running = hrtimer_cancel(&vcpu->arch.comparecount_timer); + + /* Nothing should be waiting on the timeout */ + kvm_mips_callbacks->queue_timer_int(vcpu); + + /* + * Restart the timer if it was running based on the expiry time + * we read, so that we don't push it back 2 periods. + */ + if (running) { + expires = ktime_add_ns(expires, + vcpu->arch.count_period); + hrtimer_start(&vcpu->arch.comparecount_timer, expires, + HRTIMER_MODE_ABS); + } + } + + /* Return the biased and scaled guest CP0_Count */ + return vcpu->arch.count_bias + kvm_mips_ktime_to_count(vcpu, now); +} + +/** + * kvm_mips_read_count() - Read the current count value. + * @vcpu: Virtual CPU. + * + * Read the current guest CP0_Count value, taking into account whether the timer + * is stopped. + * + * Returns: The current guest CP0_Count value. + */ +uint32_t kvm_mips_read_count(struct kvm_vcpu *vcpu) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + + /* If count disabled just read static copy of count */ + if (kvm_mips_count_disabled(vcpu)) + return kvm_read_c0_guest_count(cop0); + + return kvm_mips_read_count_running(vcpu, ktime_get()); +} + +/** + * kvm_mips_freeze_hrtimer() - Safely stop the hrtimer. + * @vcpu: Virtual CPU. + * @count: Output pointer for CP0_Count value at point of freeze. + * + * Freeze the hrtimer safely and return both the ktime and the CP0_Count value + * at the point it was frozen. It is guaranteed that any pending interrupts at + * the point it was frozen are handled, and none after that point. + * + * This is useful where the time/CP0_Count is needed in the calculation of the + * new parameters. + * + * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is running). + * + * Returns: The ktime at the point of freeze. + */ +static ktime_t kvm_mips_freeze_hrtimer(struct kvm_vcpu *vcpu, + uint32_t *count) +{ + ktime_t now; + + /* stop hrtimer before finding time */ + hrtimer_cancel(&vcpu->arch.comparecount_timer); + now = ktime_get(); + + /* find count at this point and handle pending hrtimer */ + *count = kvm_mips_read_count_running(vcpu, now); + + return now; +} + - /* If COUNT is enabled */ - if (!(kvm_read_c0_guest_cause(cop0) & CAUSEF_DC)) { - hrtimer_try_to_cancel(&vcpu->arch.comparecount_timer); - hrtimer_start(&vcpu->arch.comparecount_timer, - ktime_set(0, MS_TO_NS(10)), HRTIMER_MODE_REL); +/** + * kvm_mips_resume_hrtimer() - Resume hrtimer, updating expiry. + * @vcpu: Virtual CPU. + * @now: ktime at point of resume. + * @count: CP0_Count at point of resume. + * + * Resumes the timer and updates the timer expiry based on @now and @count. + * This can be used in conjunction with kvm_mips_freeze_timer() when timer + * parameters need to be changed. + * + * It is guaranteed that a timer interrupt immediately after resume will be + * handled, but not if CP_Compare is exactly at @count. That case is already + * handled by kvm_mips_freeze_timer(). + * + * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is running). + */ +static void kvm_mips_resume_hrtimer(struct kvm_vcpu *vcpu, + ktime_t now, uint32_t count) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + uint32_t compare; + u64 delta; + ktime_t expire; + + /* Calculate timeout (wrap 0 to 2^32) */ + compare = kvm_read_c0_guest_compare(cop0); + delta = (u64)(uint32_t)(compare - count - 1) + 1; + delta = div_u64(delta * NSEC_PER_SEC, vcpu->arch.count_hz); + expire = ktime_add_ns(now, delta); + + /* Update hrtimer to use new timeout */ + hrtimer_cancel(&vcpu->arch.comparecount_timer); + hrtimer_start(&vcpu->arch.comparecount_timer, expire, HRTIMER_MODE_ABS); +} + +/** + * kvm_mips_update_hrtimer() - Update next expiry time of hrtimer. + * @vcpu: Virtual CPU. + * + * Recalculates and updates the expiry time of the hrtimer. This can be used + * after timer parameters have been altered which do not depend on the time that + * the change occurs (in those cases kvm_mips_freeze_hrtimer() and + * kvm_mips_resume_hrtimer() are used directly). + * + * It is guaranteed that no timer interrupts will be lost in the process. + * + * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is running). + */ +static void kvm_mips_update_hrtimer(struct kvm_vcpu *vcpu) +{ + ktime_t now; + uint32_t count; + + /* + * freeze_hrtimer takes care of a timer interrupts <= count, and + * resume_hrtimer the hrtimer takes care of a timer interrupts > count. + */ + now = kvm_mips_freeze_hrtimer(vcpu, &count); + kvm_mips_resume_hrtimer(vcpu, now, count); +} + +/** + * kvm_mips_write_count() - Modify the count and update timer. + * @vcpu: Virtual CPU. + * @count: Guest CP0_Count value to set. + * + * Sets the CP0_Count value and updates the timer accordingly. + */ +void kvm_mips_write_count(struct kvm_vcpu *vcpu, uint32_t count) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + ktime_t now; + + /* Calculate bias */ + now = kvm_mips_count_time(vcpu); + vcpu->arch.count_bias = count - kvm_mips_ktime_to_count(vcpu, now); + + if (kvm_mips_count_disabled(vcpu)) + /* The timer's disabled, adjust the static count */ + kvm_write_c0_guest_count(cop0, count); + else + /* Update timeout */ + kvm_mips_resume_hrtimer(vcpu, now, count); +} + +/** + * kvm_mips_init_count() - Initialise timer. + * @vcpu: Virtual CPU. + * + * Initialise the timer to a sensible frequency, namely 100MHz, zero it, and set + * it going if it's enabled. + */ +void kvm_mips_init_count(struct kvm_vcpu *vcpu) +{ + /* 100 MHz */ + vcpu->arch.count_hz = 100*1000*1000; + vcpu->arch.count_period = div_u64((u64)NSEC_PER_SEC << 32, + vcpu->arch.count_hz); + vcpu->arch.count_dyn_bias = 0; + + /* Starting at 0 */ + kvm_mips_write_count(vcpu, 0); +} + +/** + * kvm_mips_set_count_hz() - Update the frequency of the timer. + * @vcpu: Virtual CPU. + * @count_hz: Frequency of CP0_Count timer in Hz. + * + * Change the frequency of the CP0_Count timer. This is done atomically so that + * CP0_Count is continuous and no timer interrupt is lost. + * + * Returns: -EINVAL if @count_hz is out of range. + * 0 on success. + */ +int kvm_mips_set_count_hz(struct kvm_vcpu *vcpu, s64 count_hz) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + int dc; + ktime_t now; + u32 count; + + /* ensure the frequency is in a sensible range... */ + if (count_hz <= 0 || count_hz > NSEC_PER_SEC) + return -EINVAL; + /* ... and has actually changed */ + if (vcpu->arch.count_hz == count_hz) + return 0; + + /* Safely freeze timer so we can keep it continuous */ + dc = kvm_mips_count_disabled(vcpu); + if (dc) { + now = kvm_mips_count_time(vcpu); + count = kvm_read_c0_guest_count(cop0); } else { - hrtimer_try_to_cancel(&vcpu->arch.comparecount_timer); + now = kvm_mips_freeze_hrtimer(vcpu, &count); } - return er; + /* Update the frequency */ + vcpu->arch.count_hz = count_hz; + vcpu->arch.count_period = div_u64((u64)NSEC_PER_SEC << 32, count_hz); + vcpu->arch.count_dyn_bias = 0; + + /* Calculate adjusted bias so dynamic count is unchanged */ + vcpu->arch.count_bias = count - kvm_mips_ktime_to_count(vcpu, now); + + /* Update and resume hrtimer */ + if (!dc) + kvm_mips_resume_hrtimer(vcpu, now, count); + return 0; +} + +/** + * kvm_mips_write_compare() - Modify compare and update timer. + * @vcpu: Virtual CPU. + * @compare: New CP0_Compare value. + * + * Update CP0_Compare to a new value and update the timeout. + */ +void kvm_mips_write_compare(struct kvm_vcpu *vcpu, uint32_t compare) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + + /* if unchanged, must just be an ack */ + if (kvm_read_c0_guest_compare(cop0) == compare) + return; + + /* Update compare */ + kvm_write_c0_guest_compare(cop0, compare); + + /* Update timeout if count enabled */ + if (!kvm_mips_count_disabled(vcpu)) + kvm_mips_update_hrtimer(vcpu); +} + +/** + * kvm_mips_count_disable() - Disable count. + * @vcpu: Virtual CPU. + * + * Disable the CP0_Count timer. A timer interrupt on or before the final stop + * time will be handled but not after. + * + * Assumes CP0_Count was previously enabled but now Guest.CP0_Cause.DC or + * count_ctl.DC has been set (count disabled). + * + * Returns: The time that the timer was stopped. + */ +static ktime_t kvm_mips_count_disable(struct kvm_vcpu *vcpu) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + uint32_t count; + ktime_t now; + + /* Stop hrtimer */ + hrtimer_cancel(&vcpu->arch.comparecount_timer); + + /* Set the static count from the dynamic count, handling pending TI */ + now = ktime_get(); + count = kvm_mips_read_count_running(vcpu, now); + kvm_write_c0_guest_count(cop0, count); + + return now; +} + +/** + * kvm_mips_count_disable_cause() - Disable count using CP0_Cause.DC. + * @vcpu: Virtual CPU. + * + * Disable the CP0_Count timer and set CP0_Cause.DC. A timer interrupt on or + * before the final stop time will be handled if the timer isn't disabled by + * count_ctl.DC, but not after. + * + * Assumes CP0_Cause.DC is clear (count enabled). + */ +void kvm_mips_count_disable_cause(struct kvm_vcpu *vcpu) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + + kvm_set_c0_guest_cause(cop0, CAUSEF_DC); + if (!(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC)) + kvm_mips_count_disable(vcpu); +} + +/** + * kvm_mips_count_enable_cause() - Enable count using CP0_Cause.DC. + * @vcpu: Virtual CPU. + * + * Enable the CP0_Count timer and clear CP0_Cause.DC. A timer interrupt after + * the start time will be handled if the timer isn't disabled by count_ctl.DC, + * potentially before even returning, so the caller should be careful with + * ordering of CP0_Cause modifications so as not to lose it. + * + * Assumes CP0_Cause.DC is set (count disabled). + */ +void kvm_mips_count_enable_cause(struct kvm_vcpu *vcpu) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + uint32_t count; + + kvm_clear_c0_guest_cause(cop0, CAUSEF_DC); + + /* + * Set the dynamic count to match the static count. + * This starts the hrtimer if count_ctl.DC allows it. + * Otherwise it conveniently updates the biases. + */ + count = kvm_read_c0_guest_count(cop0); + kvm_mips_write_count(vcpu, count); +} + +/** + * kvm_mips_set_count_ctl() - Update the count control KVM register. + * @vcpu: Virtual CPU. + * @count_ctl: Count control register new value. + * + * Set the count control KVM register. The timer is updated accordingly. + * + * Returns: -EINVAL if reserved bits are set. + * 0 on success. + */ +int kvm_mips_set_count_ctl(struct kvm_vcpu *vcpu, s64 count_ctl) +{ + struct mips_coproc *cop0 = vcpu->arch.cop0; + s64 changed = count_ctl ^ vcpu->arch.count_ctl; + s64 delta; + ktime_t expire, now; + uint32_t count, compare; + + /* Only allow defined bits to be changed */ + if (changed & ~(s64)(KVM_REG_MIPS_COUNT_CTL_DC)) + return -EINVAL; + + /* Apply new value */ + vcpu->arch.count_ctl = count_ctl; + + /* Master CP0_Count disable */ + if (changed & KVM_REG_MIPS_COUNT_CTL_DC) { + /* Is CP0_Cause.DC already disabling CP0_Count? */ + if (kvm_read_c0_guest_cause(cop0) & CAUSEF_DC) { + if (count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) + /* Just record the current time */ + vcpu->arch.count_resume = ktime_get(); + } else if (count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) { + /* disable timer and record current time */ + vcpu->arch.count_resume = kvm_mips_count_disable(vcpu); + } else { + /* + * Calculate timeout relative to static count at resume + * time (wrap 0 to 2^32). + */ + count = kvm_read_c0_guest_count(cop0); + compare = kvm_read_c0_guest_compare(cop0); + delta = (u64)(uint32_t)(compare - count - 1) + 1; + delta = div_u64(delta * NSEC_PER_SEC, + vcpu->arch.count_hz); + expire = ktime_add_ns(vcpu->arch.count_resume, delta); + + /* Handle pending interrupt */ + now = ktime_get(); + if (ktime_compare(now, expire) >= 0) + /* Nothing should be waiting on the timeout */ + kvm_mips_callbacks->queue_timer_int(vcpu); + + /* Resume hrtimer without changing bias */ + count = kvm_mips_read_count_running(vcpu, now); + kvm_mips_resume_hrtimer(vcpu, now, count); + } + } + + return 0; +} + +/** + * kvm_mips_set_count_resume() - Update the count resume KVM register. + * @vcpu: Virtual CPU. + * @count_resume: Count resume register new value. + * + * Set the count resume KVM register. + * + * Returns: -EINVAL if out of valid range (0..now). + * 0 on success. + */ +int kvm_mips_set_count_resume(struct kvm_vcpu *vcpu, s64 count_resume) +{ + /* + * It doesn't make sense for the resume time to be in the future, as it + * would be possible for the next interrupt to be more than a full + * period in the future. + */ + if (count_resume < 0 || count_resume > ktime_to_ns(ktime_get())) + return -EINVAL; + + vcpu->arch.count_resume = ns_to_ktime(count_resume); + return 0; +} + +/** + * kvm_mips_count_timeout() - Push timer forward on timeout. + * @vcpu: Virtual CPU. + * + * Handle an hrtimer event by push the hrtimer forward a period. + * + * Returns: The hrtimer_restart value to return to the hrtimer subsystem. + */ +enum hrtimer_restart kvm_mips_count_timeout(struct kvm_vcpu *vcpu) +{ + /* Add the Count period to the current expiry time */ + hrtimer_add_expires_ns(&vcpu->arch.comparecount_timer, + vcpu->arch.count_period); + return HRTIMER_RESTART; } enum emulation_result kvm_mips_emul_eret(struct kvm_vcpu *vcpu) @@ -471,8 +967,7 @@ kvm_mips_emulate_CP0(uint32_t inst, uint32_t *opc, uint32_t cause, #endif /* Get reg */ if ((rd == MIPS_CP0_COUNT) && (sel == 0)) { - /* XXXKYMA: Run the Guest count register @ 1/4 the rate of the host */ - vcpu->arch.gprs[rt] = (read_c0_count() >> 2); + vcpu->arch.gprs[rt] = kvm_mips_read_count(vcpu); } else if ((rd == MIPS_CP0_ERRCTL) && (sel == 0)) { vcpu->arch.gprs[rt] = 0x0; #ifdef CONFIG_KVM_MIPS_DYN_TRANS @@ -539,10 +1034,7 @@ kvm_mips_emulate_CP0(uint32_t inst, uint32_t *opc, uint32_t cause, } /* Are we writing to COUNT */ else if ((rd == MIPS_CP0_COUNT) && (sel == 0)) { - /* Linux doesn't seem to write into COUNT, we throw an error - * if we notice a write to COUNT - */ - /*er = EMULATE_FAIL; */ + kvm_mips_write_count(vcpu, vcpu->arch.gprs[rt]); goto done; } else if ((rd == MIPS_CP0_COMPARE) && (sel == 0)) { kvm_debug("[%#x] MTCz, COMPARE %#lx <- %#lx\n", @@ -552,8 +1044,8 @@ kvm_mips_emulate_CP0(uint32_t inst, uint32_t *opc, uint32_t cause, /* If we are writing to COMPARE */ /* Clear pending timer interrupt, if any */ kvm_mips_callbacks->dequeue_timer_int(vcpu); - kvm_write_c0_guest_compare(cop0, - vcpu->arch.gprs[rt]); + kvm_mips_write_compare(vcpu, + vcpu->arch.gprs[rt]); } else if ((rd == MIPS_CP0_STATUS) && (sel == 0)) { kvm_write_c0_guest_status(cop0, vcpu->arch.gprs[rt]); @@ -564,6 +1056,20 @@ kvm_mips_emulate_CP0(uint32_t inst, uint32_t *opc, uint32_t cause, #ifdef CONFIG_KVM_MIPS_DYN_TRANS kvm_mips_trans_mtc0(inst, opc, vcpu); #endif + } else if ((rd == MIPS_CP0_CAUSE) && (sel == 0)) { + uint32_t old_cause, new_cause; + old_cause = kvm_read_c0_guest_cause(cop0); + new_cause = vcpu->arch.gprs[rt]; + /* Update R/W bits */ + kvm_change_c0_guest_cause(cop0, 0x08800300, + new_cause); + /* DC bit enabling/disabling timer? */ + if ((old_cause ^ new_cause) & CAUSEF_DC) { + if (new_cause & CAUSEF_DC) + kvm_mips_count_disable_cause(vcpu); + else + kvm_mips_count_enable_cause(vcpu); + } } else { cop0->reg[rd][sel] = vcpu->arch.gprs[rt]; #ifdef CONFIG_KVM_MIPS_DYN_TRANS @@ -887,7 +1393,7 @@ int kvm_mips_sync_icache(unsigned long va, struct kvm_vcpu *vcpu) printk("%s: va: %#lx, unmapped: %#x\n", __func__, va, CKSEG0ADDR(pa)); - mips32_SyncICache(CKSEG0ADDR(pa), 32); + local_flush_icache_range(CKSEG0ADDR(pa), 32); return 0; } @@ -1325,8 +1831,12 @@ kvm_mips_handle_tlbmod(unsigned long cause, uint32_t *opc, struct kvm_run *run, struct kvm_vcpu *vcpu) { enum emulation_result er = EMULATE_DONE; - #ifdef DEBUG + struct mips_coproc *cop0 = vcpu->arch.cop0; + unsigned long entryhi = (vcpu->arch.host_cp0_badvaddr & VPN2_MASK) | + (kvm_read_c0_guest_entryhi(cop0) & ASID_MASK); + int index; + /* * If address not in the guest TLB, then we are in trouble */ @@ -1553,8 +2063,7 @@ kvm_mips_handle_ri(unsigned long cause, uint32_t *opc, current_cpu_data.icache.linesz); break; case 2: /* Read count register */ - printk("RDHWR: Cont register\n"); - arch->gprs[rt] = kvm_read_c0_guest_count(cop0); + arch->gprs[rt] = kvm_mips_read_count(vcpu); break; case 3: /* Count register resolution */ switch (current_cpu_data.cputype) { @@ -1810,11 +2319,9 @@ kvm_mips_handle_tlbmiss(unsigned long cause, uint32_t *opc, er = EMULATE_FAIL; } } else { -#ifdef DEBUG kvm_debug ("Injecting hi: %#lx, lo0: %#lx, lo1: %#lx into shadow host TLB\n", tlb->tlb_hi, tlb->tlb_lo0, tlb->tlb_lo1); -#endif /* OK we have a Guest TLB entry, now inject it into the shadow host TLB */ kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, NULL, NULL); |