> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuzn...@redhat.com]
> Sent: Friday, April 7, 2017 04:27
> To: de...@linuxdriverproject.org; x...@kernel.org
> Cc: linux-ker...@vger.kernel.org; KY Srinivasan <k...@microsoft.com>;
> Haiyang Zhang <haiya...@microsoft.com>; Stephen Hemminger
> <sthem...@microsoft.com>; Thomas Gleixner <t...@linutronix.de>; Ingo
> Molnar <mi...@redhat.com>; H. Peter Anvin <h...@zytor.com>; Steven
> Rostedt <rost...@goodmis.org>; Jork Loeser <jork.loe...@microsoft.com>
> Subject: [PATCH 6/7] x86/hyper-v: use hypercall for remove TLB flush
> diff --git a/arch/x86/hyperv/mmu.c b/arch/x86/hyperv/mmu.c new file
> mode 100644 index 0000000..fb487cb
> --- /dev/null
> +++ b/arch/x86/hyperv/mmu.c
> @@ -0,0 +1,128 @@
> +#include <linux/types.h>
> +#include <linux/hyperv.h>
> +#include <linux/slab.h>
> +#include <asm/mshyperv.h>
> +#include <asm/tlbflush.h>
> +#include <asm/msr.h>
> +#include <asm/fpu/api.h>
> +
> +/*
> + * Arbitrary number; we need to pre-allocate per-cpu struct for doing
> +TLB
> + * flush hypercalls and we need to pick a size. '16' means we'll be
> +able
> + * to flush 16 * 4096 pages (256MB) with one hypercall.
> + */
> +#define HV_MMU_MAX_GVAS 16
> +
> +/* HvFlushVirtualAddressSpace*, HvFlushVirtualAddressList hypercalls */
> +struct hv_flush_pcpu {
> + struct {
> + __u64 address_space;
> + __u64 flags;
> + __u64 processor_mask;
> + __u64 gva_list[HV_MMU_MAX_GVAS];
> + } flush;
> +
> + spinlock_t lock;
> +};
Does this need an alignment declaration, so that the flush portion never
crosses a page boundary when allocated with alloc_percpu()?
> +
> +static struct hv_flush_pcpu __percpu *pcpu_flush;
> +
> +static void hyperv_flush_tlb_others(const struct cpumask *cpus,
> + struct mm_struct *mm, unsigned long
> start,
> + unsigned long end)
> +{
> + struct hv_flush_pcpu *flush;
> + unsigned long cur, flags;
> + u64 status = -1ULL;
> + int cpu, vcpu, gva_n;
> +
> + if (!pcpu_flush || !hv_hypercall_pg)
> + goto do_native;
> +
> + if (cpumask_empty(cpus))
> + return;
> +
> + flush = this_cpu_ptr(pcpu_flush);
> + spin_lock_irqsave(&flush->lock, flags);
What purpose does the spinlock on the CPU-local struct serve? Would a
local_irq_save() do?
Could this be called from NMI context, such as from the debugger?
Could this be a long-running loop, e.g. due to a large start/end range? If so,
consider disabling interrupts only in the inner loop / flush the entire space?
Regards,
Jork
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