Messages in this thread | | | Subject | Re: [PATCH] arm/arm64: xen: Fix to convert percpu address to gfn correctly | From | Julien Grall <> | Date | Mon, 5 Oct 2020 19:18:47 +0100 |
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Hi Masami,
On 05/10/2020 14:39, Masami Hiramatsu wrote: > Use per_cpu_ptr_to_phys() instead of virt_to_phys() for per-cpu > address conversion. > > In xen_starting_cpu(), per-cpu xen_vcpu_info address is converted > to gfn by virt_to_gfn() macro. However, since the virt_to_gfn(v) > assumes the given virtual address is in contiguous kernel memory > area, it can not convert the per-cpu memory if it is allocated on > vmalloc area (depends on CONFIG_SMP).
Are you sure about this? I have a .config with CONFIG_SMP=y where the per-cpu region for CPU0 is allocated outside of vmalloc area.
However, I was able to trigger the bug as soon as CONFIG_NUMA_BALANCING was enabled.
[...]
> Fixes: 250c9af3d831 ("arm/xen: Add support for 64KB page granularity")
FWIW, I think the bug was already present before 250c9af3d831.
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> > --- > arch/arm/xen/enlighten.c | 2 +- > include/xen/arm/page.h | 3 +++ > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c > index e93145d72c26..a6ab3689b2f4 100644 > --- a/arch/arm/xen/enlighten.c > +++ b/arch/arm/xen/enlighten.c > @@ -150,7 +150,7 @@ static int xen_starting_cpu(unsigned int cpu) > pr_info("Xen: initializing cpu%d\n", cpu); > vcpup = per_cpu_ptr(xen_vcpu_info, cpu); > > - info.mfn = virt_to_gfn(vcpup); > + info.mfn = percpu_to_gfn(vcpup); > info.offset = xen_offset_in_page(vcpup); > > err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cpu), > diff --git a/include/xen/arm/page.h b/include/xen/arm/page.h > index 39df751d0dc4..ac1b65470563 100644 > --- a/include/xen/arm/page.h > +++ b/include/xen/arm/page.h > @@ -83,6 +83,9 @@ static inline unsigned long bfn_to_pfn(unsigned long bfn) > }) > #define gfn_to_virt(m) (__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT)) > > +#define percpu_to_gfn(v) \ > + (pfn_to_gfn(per_cpu_ptr_to_phys(v) >> XEN_PAGE_SHIFT)) > + > /* Only used in PV code. But ARM guests are always HVM. */ > static inline xmaddr_t arbitrary_virt_to_machine(void *vaddr) > { >
Cheers,
-- Julien Grall
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