linux-kernel - Re: [PATCH v3 08/11] kvm: arm64: Create separate instances of kvm_host

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Message-ID: <20200918115821.GA31096@willie-the-truck>
Date:   Fri, 18 Sep 2020 12:58:22 +0100
From:   Will Deacon <will@...nel.org>
To:     David Brazdil <dbrazdil@...gle.com>
Cc:     kvmarm@...ts.cs.columbia.edu,
        Catalin Marinas <catalin.marinas@....com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com
Subject: Re: [PATCH v3 08/11] kvm: arm64: Create separate instances of
 kvm_host_data for VHE/nVHE

On Wed, Sep 16, 2020 at 06:34:36PM +0100, David Brazdil wrote:
> Host CPU context is stored in a global per-cpu variable `kvm_host_data`.
> In preparation for introducing independent per-CPU region for nVHE hyp,
> create two separate instances of `kvm_host_data`, one for VHE and one
> for nVHE.
> 
> Signed-off-by: David Brazdil <dbrazdil@...gle.com>
> ---
>  arch/arm64/include/asm/kvm_host.h | 2 +-
>  arch/arm64/kernel/image-vars.h    | 1 -
>  arch/arm64/kvm/arm.c              | 5 ++---
>  arch/arm64/kvm/hyp/nvhe/switch.c  | 3 +++
>  arch/arm64/kvm/hyp/vhe/switch.c   | 3 +++
>  arch/arm64/kvm/pmu.c              | 8 ++++----
>  6 files changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 905c2b87e05a..5d8c63f5e97e 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -565,7 +565,7 @@ void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
>  
>  struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
>  
> -DECLARE_PER_CPU(kvm_host_data_t, kvm_host_data);
> +DECLARE_KVM_HYP_PER_CPU(kvm_host_data_t, kvm_host_data);
>  
>  static inline void kvm_init_host_cpu_context(struct kvm_cpu_context *cpu_ctxt)
>  {
> diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
> index 59d12a0b4622..80da861b8180 100644
> --- a/arch/arm64/kernel/image-vars.h
> +++ b/arch/arm64/kernel/image-vars.h
> @@ -67,7 +67,6 @@ KVM_NVHE_ALIAS(kvm_patch_vector_branch);
>  KVM_NVHE_ALIAS(kvm_update_va_mask);
>  
>  /* Global kernel state accessed by nVHE hyp code. */
> -KVM_NVHE_ALIAS(kvm_host_data);
>  KVM_NVHE_ALIAS(kvm_vgic_global_state);
>  
>  /* Kernel constant needed to compute idmap addresses. */
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 3bdc2661d276..7af9809fa193 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -46,7 +46,6 @@
>  __asm__(".arch_extension	virt");
>  #endif
>  
> -DEFINE_PER_CPU(kvm_host_data_t, kvm_host_data);
>  static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
>  
>  /* The VMID used in the VTTBR */
> @@ -1308,7 +1307,7 @@ static void cpu_hyp_reset(void)
>  
>  static void cpu_hyp_reinit(void)
>  {
> -	kvm_init_host_cpu_context(&this_cpu_ptr(&kvm_host_data)->host_ctxt);
> +	kvm_init_host_cpu_context(&this_cpu_ptr_hyp(kvm_host_data)->host_ctxt);
>  
>  	cpu_hyp_reset();
>  
> @@ -1543,7 +1542,7 @@ static int init_hyp_mode(void)
>  	for_each_possible_cpu(cpu) {
>  		kvm_host_data_t *cpu_data;
>  
> -		cpu_data = per_cpu_ptr(&kvm_host_data, cpu);
> +		cpu_data = per_cpu_ptr_hyp(kvm_host_data, cpu);

I stand by my earlier comment to add _sym here, given that the ampersand
gets dropped from the argument.

So assuming you do that in the earlier patch:

Acked-by: Will Deacon <will@...nel.org>

Will