Re: [PATCH v2 12/14] KVM: SVM: Drop redundant svm_sev_enabled() helper

Tom Lendacky
2021-01-14T22:52:42Z

On 1/13/21 6:37 PM, Sean Christopherson wrote:
> Replace calls to svm_sev_enabled() with direct checks on sev_enabled, or
> in the case of svm_mem_enc_op, simply drop the call to svm_sev_enabled().
> This effectively replaces checks against a valid max_sev_asid with checks
> against sev_enabled. sev_enabled is forced off by sev_hardware_setup()
> if max_sev_asid is invalid, all call sites are guaranteed to run after
> sev_hardware_setup(), and all of the checks care about SEV being fully
> enabled (as opposed to intentionally handling the scenario where
> max_sev_asid is valid but SEV enabling fails due to OOM).
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Ultimately the #ifdef CONFIG_KVM_AMD_SEV that you added that #defines
sev_enabled and sev_es_enabled to false, resolves the build issue when
kvm_amd is built into the kernel and ccp is built as a module, for which
svm_sev_enabled() was originally created.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>

> ---
> arch/x86/kvm/svm/sev.c | 6 +++---
> arch/x86/kvm/svm/svm.h | 5 -----
> 2 files changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index a2c3e2d42a7f..7e14514dd083 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1057,7 +1057,7 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
> struct kvm_sev_cmd sev_cmd;
> int r;
>
> - if (!svm_sev_enabled() || !sev_enabled)
> + if (!sev_enabled)
> return -ENOTTY;
>
> if (!argp)
> @@ -1321,7 +1321,7 @@ void __init sev_hardware_setup(void)
>
> void sev_hardware_teardown(void)
> {
> - if (!svm_sev_enabled())
> + if (!sev_enabled)
> return;
>
> bitmap_free(sev_asid_bitmap);
> @@ -1332,7 +1332,7 @@ void sev_hardware_teardown(void)
>
> int sev_cpu_init(struct svm_cpu_data *sd)
> {
> - if (!svm_sev_enabled())
> + if (!sev_enabled)
> return 0;
>
> sd->sev_vmcbs = kmalloc_array(max_sev_asid + 1, sizeof(void *),
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 4eb4bab0ca3e..8cb4395b58a0 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -569,11 +569,6 @@ void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
>
> extern unsigned int max_sev_asid;
>
> -static inline bool svm_sev_enabled(void)
> -{
> - return IS_ENABLED(CONFIG_KVM_AMD_SEV) ? max_sev_asid : 0;
> -}
> -
> void sev_vm_destroy(struct kvm *kvm);
> int svm_mem_enc_op(struct kvm *kvm, void __user *argp);
> int svm_register_enc_region(struct kvm *kvm,
>