Re: [PATCH v3 16/18] KVM: arm64: nVHE: Migrate hyp interface to SMCCC

From: Marc Zyngier <maz@kernel.org>
To: Andrew Scull <ascull@google.com>
Cc: kernel-team@android.com, suzuki.poulose@arm.com,
	catalin.marinas@arm.com, james.morse@arm.com,
	linux-arm-kernel@lists.infradead.org,
	Sudeep Holla <sudeep.holla@arm.com>,
	David Brazdil <dbrazdil@google.com>,
	will@kernel.org, kvmarm@lists.cs.columbia.edu,
	julien.thierry.kdev@gmail.com
Subject: Re: [PATCH v3 16/18] KVM: arm64: nVHE: Migrate hyp interface to SMCCC
Date: Mon, 07 Sep 2020 15:20:07 +0100	[thread overview]
Message-ID: <87o8mhlld4.wl-maz@kernel.org> (raw)
In-Reply-To: <20200903135307.251331-17-ascull@google.com>

On Thu, 03 Sep 2020 14:53:05 +0100,
Andrew Scull <ascull@google.com> wrote:
> 
> Rather than passing arbitrary function pointers to run at hyp, define
> and equivalent set of SMCCC functions.
> 
> Since the SMCCC functions are strongly tied to the original function
> prototypes, it is not expected for the host to ever call an invalid ID
> but a warning is raised if this does ever occur.
> 
> As __kvm_vcpu_run is used for every switch between the host and a guest,
> it is explicitly singled out to be identified before the other function
> IDs to improve the performance of the hot path.
> 
> Signed-off-by: Andrew Scull <ascull@google.com>
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  arch/arm64/include/asm/kvm_asm.h   |  24 ++++++
>  arch/arm64/include/asm/kvm_host.h  |  25 ++++---
>  arch/arm64/kvm/arm.c               |   2 +-
>  arch/arm64/kvm/hyp.S               |  24 ++----
>  arch/arm64/kvm/hyp/nvhe/hyp-main.c | 113 +++++++++++++++++++++++++----
>  5 files changed, 145 insertions(+), 43 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 4bbde3d3989c..4a73f1349151 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -38,6 +38,30 @@
>  
>  #define __SMCCC_WORKAROUND_1_SMC_SZ 36
>  
> +#define KVM_HOST_SMCCC_ID(id)						\
> +	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
> +			   ARM_SMCCC_SMC_64,				\
> +			   ARM_SMCCC_OWNER_STANDARD_HYP,		\
> +			   (id))
> +
> +#define KVM_HOST_SMCCC_FUNC(name) KVM_HOST_SMCCC_ID(__KVM_HOST_SMCCC_FUNC_##name)
> +
> +#define __KVM_HOST_SMCCC_FUNC___kvm_hyp_init			0
> +#define __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context		1
> +#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_ipa		2
> +#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid		3
> +#define __KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_local_vmid	4
> +#define __KVM_HOST_SMCCC_FUNC___kvm_timer_set_cntvoff		5
> +#define __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run			6
> +#define __KVM_HOST_SMCCC_FUNC___kvm_enable_ssbs			7
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_get_ich_vtr_el2		8
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_read_vmcr		9
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_write_vmcr		10
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_init_lrs		11
> +#define __KVM_HOST_SMCCC_FUNC___kvm_get_mdcr_el2		12
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_save_aprs		13
> +#define __KVM_HOST_SMCCC_FUNC___vgic_v3_restore_aprs		14

Wait. This looks broken. How do you distinguish between these and the
stubs?

	M.

-- 
Without deviation from the norm, progress is not possible.

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