On Mon, Jul 13, 2020 at 10:05:02PM +0100, Andrew Scull wrote:
> Move the clearing of KVM_ARM64_DEBUG_DIRTY from being one of the last
> things hyp does before exiting to the host to being one of the first
> things the host does after hyp exits.
>
> This means the host always manages the state of the bit and hyp simply
> respects that in the context switch.
>
> No functional change.
>
> Signed-off-by: Andrew Scull <ascull@xxxxxxxxxx>
Seems reasonable, though we have to map the vcpu arch flags into hyp
anyway. For FPSIMD we do maintain these flags from hyp, in order to
void mapping in host-specific stuff (the thread flags).
So maybe this change isn't that useful?
I don't have a strong opinion though. If this change fits in better
with the broader KVM work you're doing, I don't see a problem with it.
So, FWIW:
Reviewed-by: Dave Martin <Dave.Martin@xxxxxxx>
> ---
> arch/arm64/include/asm/kvm_host.h | 2 +-
> arch/arm64/kvm/debug.c | 2 ++
> arch/arm64/kvm/hyp/include/hyp/debug-sr.h | 2 --
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index e1a32c0707bb..b06f24b5f443 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -404,7 +404,7 @@ struct kvm_vcpu_arch {
> })
>
> /* vcpu_arch flags field values: */
> -#define KVM_ARM64_DEBUG_DIRTY (1 << 0)
> +#define KVM_ARM64_DEBUG_DIRTY (1 << 0) /* vcpu is using debug */
> #define KVM_ARM64_FP_ENABLED (1 << 1) /* guest FP regs loaded */
> #define KVM_ARM64_FP_HOST (1 << 2) /* host FP regs loaded */
> #define KVM_ARM64_HOST_SVE_IN_USE (1 << 3) /* backup for host TIF_SVE */
> diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
> index 7a7e425616b5..e9932618a362 100644
> --- a/arch/arm64/kvm/debug.c
> +++ b/arch/arm64/kvm/debug.c
> @@ -209,6 +209,8 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
> {
> trace_kvm_arm_clear_debug(vcpu->guest_debug);
>
> + vcpu->arch.flags &= ~KVM_ARM64_DEBUG_DIRTY;
> +
> if (vcpu->guest_debug) {
> restore_guest_debug_regs(vcpu);
>
> diff --git a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
> index 0297dc63988c..50ca5d048017 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/debug-sr.h
> @@ -161,8 +161,6 @@ static inline void __debug_switch_to_host_common(struct kvm_vcpu *vcpu)
>
> __debug_save_state(guest_dbg, guest_ctxt);
> __debug_restore_state(host_dbg, host_ctxt);
> -
> - vcpu->arch.flags &= ~KVM_ARM64_DEBUG_DIRTY;
> }
>
> #endif /* __ARM64_KVM_HYP_DEBUG_SR_H__ */
> --
> 2.27.0.383.g050319c2ae-goog
>
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