Messages in this thread | | | Date | Mon, 18 Jul 2022 17:57:25 +0100 | From | Marc Zyngier <> | Subject | Re: [PATCH v4 11/18] KVM: arm64: Stub implementation of non-protected nVHE HYP stack unwinder |
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On 2022-07-18 17:51, Kalesh Singh wrote: > On Mon, Jul 18, 2022 at 12:31 AM Marc Zyngier <maz@kernel.org> wrote: >> >> On Fri, 15 Jul 2022 07:10:20 +0100, >> Kalesh Singh <kaleshsingh@google.com> wrote: >> > >> > Add stub implementations of non-protected nVHE stack unwinder, for >> > building. These are implemented later in this series. >> > >> > Signed-off-by: Kalesh Singh <kaleshsingh@google.com> >> > --- >> > arch/arm64/include/asm/stacktrace/nvhe.h | 22 ++++++++++++++++++++++ >> > 1 file changed, 22 insertions(+) >> > >> > diff --git a/arch/arm64/include/asm/stacktrace/nvhe.h b/arch/arm64/include/asm/stacktrace/nvhe.h >> > index 1eac4e57f2ae..36cf7858ddd8 100644 >> > --- a/arch/arm64/include/asm/stacktrace/nvhe.h >> > +++ b/arch/arm64/include/asm/stacktrace/nvhe.h >> > @@ -8,6 +8,12 @@ >> > * the HYP memory. The stack is unwinded in EL2 and dumped to a shared >> > * buffer where the host can read and print the stacktrace. >> > * >> > + * 2) Non-protected nVHE mode - the host can directly access the >> > + * HYP stack pages and unwind the HYP stack in EL1. This saves having >> > + * to allocate shared buffers for the host to read the unwinded >> > + * stacktrace. >> > + * >> > + * >> > * Copyright (C) 2022 Google LLC >> > */ >> > #ifndef __ASM_STACKTRACE_NVHE_H >> > @@ -53,5 +59,21 @@ static int notrace unwind_next(struct unwind_state *state) >> > NOKPROBE_SYMBOL(unwind_next); >> > #endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */ >> > >> > +/* >> > + * Non-protected nVHE HYP stack unwinder >> > + */ >> > +#else /* !__KVM_NVHE_HYPERVISOR__ */ >> >> I don't get this path. This either represents the VHE hypervisor or >> the kernel proper. Which one is it? > > Hi Marc. This is run from kernel proper context. And it's the > unwinding for conventional nVHE (non-protected). The unwinding is done > from the host kernel in EL1.
This really deserves a comment here, as the one you currently have is a bit misleading (and you probably want to move it below the #else).
Thanks,
M. -- Jazz is not dead. It just smells funny...
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