Re: [PATCH v5 5/9] task_isolation: Add driver-specific hooks

Mark Rutland
2020-12-02T14:19:18Z

On Mon, Nov 23, 2020 at 05:57:42PM +0000, Alex Belits wrote:
> Some drivers don't call functions that call
> task_isolation_kernel_enter() in interrupt handlers. Call it
> directly.

I don't think putting this in drivers is the right approach. IIUC we
only need to track user<->kernel transitions, and we can do that within
the architectural entry code before we ever reach irqchip code. I
suspect the current approacch is an artifact of that being difficult in
the old structure of the arch code; recent rework should address that,
and we can restruecture things further in future.

Thanks,
Mark.

> Signed-off-by: Alex Belits <abelits@marvell.com>
> ---
> drivers/irqchip/irq-armada-370-xp.c | 6 ++++++
> drivers/irqchip/irq-gic-v3.c | 3 +++
> drivers/irqchip/irq-gic.c | 3 +++
> drivers/s390/cio/cio.c | 3 +++
> 4 files changed, 15 insertions(+)
>
> diff --git a/drivers/irqchip/irq-armada-370-xp.c b/drivers/irqchip/irq-armada-370-xp.c
> index d7eb2e93db8f..4ac7babe1abe 100644
> --- a/drivers/irqchip/irq-armada-370-xp.c
> +++ b/drivers/irqchip/irq-armada-370-xp.c
> @@ -29,6 +29,7 @@
> #include <linux/slab.h>
> #include <linux/syscore_ops.h>
> #include <linux/msi.h>
> +#include <linux/isolation.h>
> #include <asm/mach/arch.h>
> #include <asm/exception.h>
> #include <asm/smp_plat.h>
> @@ -572,6 +573,7 @@ static const struct irq_domain_ops armada_370_xp_mpic_irq_ops = {
> static void armada_370_xp_handle_msi_irq(struct pt_regs *regs, bool is_chained)
> {
> u32 msimask, msinr;
> + int isol_entered = 0;
>
> msimask = readl_relaxed(per_cpu_int_base +
> ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS)
> @@ -588,6 +590,10 @@ static void armada_370_xp_handle_msi_irq(struct pt_regs *regs, bool is_chained)
> continue;
>
> if (is_chained) {
> + if (!isol_entered) {
> + task_isolation_kernel_enter();
> + isol_entered = 1;
> + }
> irq = irq_find_mapping(armada_370_xp_msi_inner_domain,
> msinr - PCI_MSI_DOORBELL_START);
> generic_handle_irq(irq);
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 16fecc0febe8..ded26dd4da0f 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -18,6 +18,7 @@
> #include <linux/percpu.h>
> #include <linux/refcount.h>
> #include <linux/slab.h>
> +#include <linux/isolation.h>
>
> #include <linux/irqchip.h>
> #include <linux/irqchip/arm-gic-common.h>
> @@ -646,6 +647,8 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs
> {
> u32 irqnr;
>
> + task_isolation_kernel_enter();
> +
> irqnr = gic_read_iar();
>
> if (gic_supports_nmi() &&
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index 6053245a4754..bb482b4ae218 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -35,6 +35,7 @@
> #include <linux/interrupt.h>
> #include <linux/percpu.h>
> #include <linux/slab.h>
> +#include <linux/isolation.h>
> #include <linux/irqchip.h>
> #include <linux/irqchip/chained_irq.h>
> #include <linux/irqchip/arm-gic.h>
> @@ -337,6 +338,8 @@ static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
> struct gic_chip_data *gic = &gic_data[0];
> void __iomem *cpu_base = gic_data_cpu_base(gic);
>
> + task_isolation_kernel_enter();
> +
> do {
> irqstat = readl_relaxed(cpu_base + GIC_CPU_INTACK);
> irqnr = irqstat & GICC_IAR_INT_ID_MASK;
> diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
> index 6d716db2a46a..beab88881b6d 100644
> --- a/drivers/s390/cio/cio.c
> +++ b/drivers/s390/cio/cio.c
> @@ -20,6 +20,7 @@
> #include <linux/kernel_stat.h>
> #include <linux/interrupt.h>
> #include <linux/irq.h>
> +#include <linux/isolation.h>
> #include <asm/cio.h>
> #include <asm/delay.h>
> #include <asm/irq.h>
> @@ -584,6 +585,8 @@ void cio_tsch(struct subchannel *sch)
> struct irb *irb;
> int irq_context;
>
> + task_isolation_kernel_enter();
> +
> irb = this_cpu_ptr(&cio_irb);
> /* Store interrupt response block to lowcore. */
> if (tsch(sch->schid, irb) != 0)
> --
> 2.20.1
>