lkml.org 
[lkml]   [2022]   [Jul]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH v5 15/17] KVM: arm64: Implement non-protected nVHE hyp stack unwinder
    Hi Kalesh,

    On Thu, Jul 21, 2022 at 6:58 AM Kalesh Singh <kaleshsingh@google.com> wrote:
    >
    > Implements the common framework necessary for unwind() to work
    > for non-protected nVHE mode:
    > - on_accessible_stack()
    > - on_overflow_stack()
    > - unwind_next()
    >
    > Non-protected nVHE unwind() is used to unwind and dump the hypervisor
    > stacktrace by the host in EL1
    >
    > Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
    > ---

    Reviewed-by: Fuad Tabba <tabba@google.com>

    Cheers,
    /fuad


    >
    > Changes in v5:
    > - Use regular comments instead of doc comments, per Fuad
    >
    > arch/arm64/include/asm/stacktrace/nvhe.h | 67 +++++++++++++++++++++++-
    > arch/arm64/kvm/arm.c | 2 +-
    > 2 files changed, 66 insertions(+), 3 deletions(-)
    >
    > diff --git a/arch/arm64/include/asm/stacktrace/nvhe.h b/arch/arm64/include/asm/stacktrace/nvhe.h
    > index c3688e717136..7a6e761aa443 100644
    > --- a/arch/arm64/include/asm/stacktrace/nvhe.h
    > +++ b/arch/arm64/include/asm/stacktrace/nvhe.h
    > @@ -120,15 +120,78 @@ NOKPROBE_SYMBOL(unwind_next);
    > * (by the host in EL1).
    > */
    >
    > +DECLARE_KVM_NVHE_PER_CPU(unsigned long [PAGE_SIZE/sizeof(long)], overflow_stack);
    > +DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info);
    > +DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
    > +
    > +/*
    > + * kvm_nvhe_stack_kern_va - Convert KVM nVHE HYP stack addresses to a kernel VAs
    > + *
    > + * The nVHE hypervisor stack is mapped in the flexible 'private' VA range, to
    > + * allow for guard pages below the stack. Consequently, the fixed offset address
    > + * translation macros won't work here.
    > + *
    > + * The kernel VA is calculated as an offset from the kernel VA of the hypervisor
    > + * stack base.
    > + *
    > + * Returns true on success and updates @addr to its corresponding kernel VA;
    > + * otherwise returns false.
    > + */
    > +static inline bool kvm_nvhe_stack_kern_va(unsigned long *addr,
    > + enum stack_type type)
    > +{
    > + struct kvm_nvhe_stacktrace_info *stacktrace_info;
    > + unsigned long hyp_base, kern_base, hyp_offset;
    > +
    > + stacktrace_info = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
    > +
    > + switch (type) {
    > + case STACK_TYPE_HYP:
    > + kern_base = (unsigned long)*this_cpu_ptr(&kvm_arm_hyp_stack_page);
    > + hyp_base = (unsigned long)stacktrace_info->stack_base;
    > + break;
    > + case STACK_TYPE_OVERFLOW:
    > + kern_base = (unsigned long)this_cpu_ptr_nvhe_sym(overflow_stack);
    > + hyp_base = (unsigned long)stacktrace_info->overflow_stack_base;
    > + break;
    > + default:
    > + return false;
    > + }
    > +
    > + hyp_offset = *addr - hyp_base;
    > +
    > + *addr = kern_base + hyp_offset;
    > +
    > + return true;
    > +}
    > +
    > static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
    > struct stack_info *info)
    > {
    > - return false;
    > + struct kvm_nvhe_stacktrace_info *stacktrace_info
    > + = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
    > + unsigned long low = (unsigned long)stacktrace_info->overflow_stack_base;
    > + unsigned long high = low + OVERFLOW_STACK_SIZE;
    > +
    > + return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
    > +}
    > +
    > +static inline bool on_hyp_stack(unsigned long sp, unsigned long size,
    > + struct stack_info *info)
    > +{
    > + struct kvm_nvhe_stacktrace_info *stacktrace_info
    > + = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
    > + unsigned long low = (unsigned long)stacktrace_info->stack_base;
    > + unsigned long high = low + PAGE_SIZE;
    > +
    > + return on_stack(sp, size, low, high, STACK_TYPE_HYP, info);
    > }
    >
    > static inline int notrace unwind_next(struct unwind_state *state)
    > {
    > - return 0;
    > + struct stack_info info;
    > +
    > + return unwind_next_common(state, &info, kvm_nvhe_stack_kern_va);
    > }
    > NOKPROBE_SYMBOL(unwind_next);
    >
    > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
    > index a0188144a122..6a64293108c5 100644
    > --- a/arch/arm64/kvm/arm.c
    > +++ b/arch/arm64/kvm/arm.c
    > @@ -49,7 +49,7 @@ DEFINE_STATIC_KEY_FALSE(kvm_protected_mode_initialized);
    >
    > DECLARE_KVM_HYP_PER_CPU(unsigned long, kvm_hyp_vector);
    >
    > -static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
    > +DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
    > unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
    > DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
    >
    > --
    > 2.37.0.170.g444d1eabd0-goog
    >

    \
     
     \ /
      Last update: 2022-07-21 12:00    [W:4.106 / U:0.508 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site