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From: Julien Thierry <julien.thierry@arm.com>
To: Sudeep Holla <sudeep.holla@arm.com>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Christoffer Dall <christoffer.dall@arm.com>,
	Marc Zyngier <marc.zyngier@arm.com>,
	James Morse <james.morse@arm.com>,
	Suzuki K Pouloze <suzuki.poulose@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v2 09/15] arm64: KVM: add support to save/restore SPE profiling buffer controls
Date: Wed, 29 May 2019 09:26:35 +0100	[thread overview]
Message-ID: <fbd9f15d-2322-5808-de62-9e1010c9c961@arm.com> (raw)
In-Reply-To: <20190523103502.25925-10-sudeep.holla@arm.com>

Hi Sudeep,

On 05/23/2019 11:34 AM, Sudeep Holla wrote:
> Currently since we don't support profiling using SPE in the guests,
> we just save the PMSCR_EL1, flush the profiling buffers and disable
> sampling. However in order to support simultaneous sampling both in
> the host and guests, we need to save and reatore the complete SPE
> profiling buffer controls' context.
> 
> Let's add the support for the same and keep it disabled for now.
> We can enable it conditionally only if guests are allowed to use
> SPE.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  arch/arm64/kvm/hyp/debug-sr.c | 44 ++++++++++++++++++++++++++++-------
>  1 file changed, 35 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
> index a2714a5eb3e9..a4e6eaf5934f 100644
> --- a/arch/arm64/kvm/hyp/debug-sr.c
> +++ b/arch/arm64/kvm/hyp/debug-sr.c
> @@ -66,7 +66,8 @@
>  	default:	write_debug(ptr[0], reg, 0);			\
>  	}
>  
> -static void __hyp_text __debug_save_spe_nvhe(struct kvm_cpu_context *ctxt)
> +static void __hyp_text
> +__debug_save_spe_nvhe(struct kvm_cpu_context *ctxt, bool full_ctxt)

Rather that add a boolean to just indicate "do more stuff" I'd suggest
having two separate functions.

Also this would be an opportunity to fix the naming of this function
which doesn't just save sve context, it also flushes the context and
disables it.

So maybe have a: void __debug_spe_flush_ctx(struct kvm_cpu_context *ctx);

Maybe adapt the name to make it understandable that it does save PMSCR.

and void __debug_spe_save_ctx(struct kvm_cpu_context *ctx);

Which would save the registers you save under the full_ctx condition.

Cheers,

Julien

  reply	other threads:[~2019-05-29  8:26 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-23 10:34 [PATCH 00/15] arm64: KVM: add SPE profiling support for guest Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 01/15] KVM: arm64: add {read,write}_sysreg_elx_s versions for new registers Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 02/15] dt-bindings: ARM SPE: highlight the need for PPI partitions on heterogeneous systems Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 03/15] arm64: KVM: reset E2PB correctly in MDCR_EL2 when exiting the guest(VHE) Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 04/15] arm64: KVM: define SPE data structure for each vcpu Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 05/15] arm64: KVM: add access handler for SPE system registers Sudeep Holla
2019-05-24 11:36   ` Julien Thierry
2019-05-24 14:12     ` Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 06/15] arm64: KVM/VHE: enable the use PMSCR_EL12 on VHE systems Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 07/15] arm64: KVM: split debug save restore across vm/traps activation Sudeep Holla
2019-05-28  8:18   ` Julien Thierry
2019-05-23 10:34 ` [PATCH v2 08/15] arm64: KVM/debug: drop pmscr_el1 and use sys_regs[PMSCR_EL1] in kvm_cpu_context Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 09/15] arm64: KVM: add support to save/restore SPE profiling buffer controls Sudeep Holla
2019-05-29  8:26   ` Julien Thierry [this message]
2019-05-23 10:34 ` [PATCH v2 10/15] arm64: KVM: enable conditional save/restore full " Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 11/15] arm64: KVM/debug: trap all accesses to SPE controls at EL1 Sudeep Holla
2019-05-23 10:34 ` [PATCH v2 12/15] KVM: arm64: add a new vcpu device control group for SPEv1 Sudeep Holla
2019-05-24 10:37   ` Marc Zyngier
2019-05-24 11:21     ` Sudeep Holla
2019-05-24 12:07       ` Marc Zyngier
2019-05-23 10:35 ` [PATCH v2 13/15] KVM: arm64: enable SPE support Sudeep Holla
2019-05-23 10:35 ` [PATCH v2 14/15][KVMTOOL] update_headers: Sync kvm UAPI headers with linux v5.2-rc1 Sudeep Holla
2019-05-23 10:35 ` [PATCH v2 15/15][KVMTOOL] kvm: add a vcpu feature for SPEv1 support Sudeep Holla

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