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
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
> ---
> 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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