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Message-ID: <20160201122907.GD1478@cbox>
Date: Mon, 1 Feb 2016 13:29:07 +0100
From: Christoffer Dall <christoffer.dall@...aro.org>
To: Marc Zyngier <marc.zyngier@....com>
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu
Subject: Re: [PATCH v2 02/21] arm64: Allow the arch timer to use the HYP timer
On Mon, Jan 25, 2016 at 03:53:36PM +0000, Marc Zyngier wrote:
> With the ARMv8.1 VHE, the kernel can run in HYP mode, and thus
> use the HYP timer instead of the normal guest timer in a mostly
> transparent way, except for the interrupt line.
>
> This patch reworks the arch timer code to allow the selection of
> the HYP PPI, possibly falling back to the guest timer if not
> available.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
> drivers/clocksource/arm_arch_timer.c | 96 ++++++++++++++++++++++--------------
> 1 file changed, 59 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index c64d543..ffe9d1c 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -67,7 +67,7 @@ static int arch_timer_ppi[MAX_TIMER_PPI];
>
> static struct clock_event_device __percpu *arch_timer_evt;
>
> -static bool arch_timer_use_virtual = true;
> +static enum ppi_nr arch_timer_uses_ppi = VIRT_PPI;
> static bool arch_timer_c3stop;
> static bool arch_timer_mem_use_virtual;
>
> @@ -263,14 +263,20 @@ static void __arch_timer_setup(unsigned type,
> clk->name = "arch_sys_timer";
> clk->rating = 450;
> clk->cpumask = cpumask_of(smp_processor_id());
> - if (arch_timer_use_virtual) {
> - clk->irq = arch_timer_ppi[VIRT_PPI];
> + clk->irq = arch_timer_ppi[arch_timer_uses_ppi];
> + switch (arch_timer_uses_ppi) {
> + case VIRT_PPI:
> clk->set_state_shutdown = arch_timer_shutdown_virt;
> clk->set_next_event = arch_timer_set_next_event_virt;
> - } else {
> - clk->irq = arch_timer_ppi[PHYS_SECURE_PPI];
> + break;
> + case PHYS_SECURE_PPI:
> + case PHYS_NONSECURE_PPI:
> + case HYP_PPI:
> clk->set_state_shutdown = arch_timer_shutdown_phys;
> clk->set_next_event = arch_timer_set_next_event_phys;
> + break;
> + default:
> + BUG();
> }
> } else {
> clk->features |= CLOCK_EVT_FEAT_DYNIRQ;
> @@ -338,17 +344,20 @@ static void arch_counter_set_user_access(void)
> arch_timer_set_cntkctl(cntkctl);
> }
>
> +static bool arch_timer_has_nonsecure_ppi(void)
> +{
> + return (arch_timer_uses_ppi == PHYS_SECURE_PPI &&
> + arch_timer_ppi[PHYS_NONSECURE_PPI]);
> +}
> +
> static int arch_timer_setup(struct clock_event_device *clk)
> {
> __arch_timer_setup(ARCH_CP15_TIMER, clk);
>
> - if (arch_timer_use_virtual)
> - enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
> - else {
> - enable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI], 0);
> - if (arch_timer_ppi[PHYS_NONSECURE_PPI])
> - enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
> - }
> + enable_percpu_irq(arch_timer_ppi[arch_timer_uses_ppi], 0);
> +
> + if (arch_timer_has_nonsecure_ppi())
> + enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
>
> arch_counter_set_user_access();
> if (IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM))
> @@ -390,7 +399,7 @@ static void arch_timer_banner(unsigned type)
> (unsigned long)arch_timer_rate / 1000000,
> (unsigned long)(arch_timer_rate / 10000) % 100,
> type & ARCH_CP15_TIMER ?
> - arch_timer_use_virtual ? "virt" : "phys" :
> + (arch_timer_uses_ppi == VIRT_PPI) ? "virt" : "phys" :
> "",
> type == (ARCH_CP15_TIMER | ARCH_MEM_TIMER) ? "/" : "",
> type & ARCH_MEM_TIMER ?
> @@ -460,7 +469,7 @@ static void __init arch_counter_register(unsigned type)
>
> /* Register the CP15 based counter if we have one */
> if (type & ARCH_CP15_TIMER) {
> - if (IS_ENABLED(CONFIG_ARM64) || arch_timer_use_virtual)
> + if (IS_ENABLED(CONFIG_ARM64) || arch_timer_uses_ppi == VIRT_PPI)
> arch_timer_read_counter = arch_counter_get_cntvct;
> else
> arch_timer_read_counter = arch_counter_get_cntpct;
> @@ -490,13 +499,9 @@ static void arch_timer_stop(struct clock_event_device *clk)
> pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
> clk->irq, smp_processor_id());
>
> - if (arch_timer_use_virtual)
> - disable_percpu_irq(arch_timer_ppi[VIRT_PPI]);
> - else {
> - disable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI]);
> - if (arch_timer_ppi[PHYS_NONSECURE_PPI])
> - disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
> - }
> + disable_percpu_irq(arch_timer_ppi[arch_timer_uses_ppi]);
> + if (arch_timer_has_nonsecure_ppi())
> + disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
>
> clk->set_state_shutdown(clk);
> }
> @@ -562,12 +567,14 @@ static int __init arch_timer_register(void)
> goto out;
> }
>
> - if (arch_timer_use_virtual) {
> - ppi = arch_timer_ppi[VIRT_PPI];
> + ppi = arch_timer_ppi[arch_timer_uses_ppi];
> + switch (arch_timer_uses_ppi) {
> + case VIRT_PPI:
> err = request_percpu_irq(ppi, arch_timer_handler_virt,
> "arch_timer", arch_timer_evt);
> - } else {
> - ppi = arch_timer_ppi[PHYS_SECURE_PPI];
> + break;
> + case PHYS_SECURE_PPI:
> + case PHYS_NONSECURE_PPI:
> err = request_percpu_irq(ppi, arch_timer_handler_phys,
> "arch_timer", arch_timer_evt);
> if (!err && arch_timer_ppi[PHYS_NONSECURE_PPI]) {
> @@ -578,6 +585,13 @@ static int __init arch_timer_register(void)
> free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
> arch_timer_evt);
> }
> + break;
> + case HYP_PPI:
> + err = request_percpu_irq(ppi, arch_timer_handler_phys,
> + "arch_timer", arch_timer_evt);
> + break;
> + default:
> + BUG();
> }
>
> if (err) {
> @@ -602,15 +616,10 @@ static int __init arch_timer_register(void)
> out_unreg_notify:
> unregister_cpu_notifier(&arch_timer_cpu_nb);
> out_free_irq:
> - if (arch_timer_use_virtual)
> - free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
> - else {
> - free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
> + free_percpu_irq(arch_timer_ppi[arch_timer_uses_ppi], arch_timer_evt);
> + if (arch_timer_has_nonsecure_ppi())
> + free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
> arch_timer_evt);
> - if (arch_timer_ppi[PHYS_NONSECURE_PPI])
> - free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
> - arch_timer_evt);
> - }
>
> out_free:
> free_percpu(arch_timer_evt);
> @@ -697,12 +706,25 @@ static void __init arch_timer_init(void)
> *
> * If no interrupt provided for virtual timer, we'll have to
> * stick to the physical timer. It'd better be accessible...
> + *
> + * On ARMv8.1 with VH extensions, the kernel runs in HYP. VHE
> + * accesses to CNTP_*_EL1 registers are silently redirected to
> + * their CNTHP_*_EL2 counterparts, and use a different PPI
> + * number.
> */
> if (is_hyp_mode_available() || !arch_timer_ppi[VIRT_PPI]) {
> - arch_timer_use_virtual = false;
> + bool has_ppi;
> +
> + if (is_kernel_in_hyp_mode()) {
> + arch_timer_uses_ppi = HYP_PPI;
> + has_ppi = !!arch_timer_ppi[HYP_PPI];
> + } else {
> + arch_timer_uses_ppi = PHYS_SECURE_PPI;
> + has_ppi = (!!arch_timer_ppi[PHYS_SECURE_PPI] ||
> + !!arch_timer_ppi[PHYS_NONSECURE_PPI]);
shouldn't this simply test the PHYS_SECURE_PPI since otherwise you could
potentially have the PHYS_NONSECURE_PPI but not PHYS_SECURE_PPI and
you'll try to request IRQ 0 for this later... ?
> + }
>
> - if (!arch_timer_ppi[PHYS_SECURE_PPI] ||
> - !arch_timer_ppi[PHYS_NONSECURE_PPI]) {
> + if (!has_ppi) {
> pr_warn("arch_timer: No interrupt available, giving up\n");
> return;
> }
> @@ -735,7 +757,7 @@ static void __init arch_timer_of_init(struct device_node *np)
> */
> if (IS_ENABLED(CONFIG_ARM) &&
> of_property_read_bool(np, "arm,cpu-registers-not-fw-configured"))
> - arch_timer_use_virtual = false;
> + arch_timer_uses_ppi = PHYS_SECURE_PPI;
>
> arch_timer_init();
> }
> --
> 2.1.4
>
Thanks,
-Christoffer
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