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SubjectRe: [PATCH] kvm/sev: remove redundant MISC_CG_RES_SEV_ES
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On 10/10/23 19:49, José Pekkarinen wrote:
> SEV-ES is an extra encrypted state that shares common resources
> with SEV. Using an extra CG for its purpose doesn't seem to
> provide much value. This patch will clean up the control group
> along with multiple checks that become redundant with it.
>
> The patch will also remove a redundant logic on sev initialization
> that produces SEV-ES to be disabled, while supported by the cpu
> and requested by the user through the sev_es parameter.

In what sense is it shared? The SEV ASIDs and the SEV-ES ASIDs are
separate (and in both cases limited) resources, and therefore they have
separate cgroups.

Paolo

> Signed-off-by: José Pekkarinen<jose.pekkarinen@foxhound.fi>
> ---
> arch/x86/kvm/svm/sev.c | 18 +++---------------
> include/linux/misc_cgroup.h | 2 --
> 2 files changed, 3 insertions(+), 17 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 07756b7348ae..8a06d92187cf 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -37,13 +37,9 @@
> * this file are not used but this file still gets compiled into the KVM AMD
> * module.
> *
> - * We will not have MISC_CG_RES_SEV and MISC_CG_RES_SEV_ES entries in the enum
> - * misc_res_type {} defined in linux/misc_cgroup.h.
> - *
> * Below macros allow compilation to succeed.
> */
> #define MISC_CG_RES_SEV MISC_CG_RES_TYPES
> -#define MISC_CG_RES_SEV_ES MISC_CG_RES_TYPES
> #endif
>
> #ifdef CONFIG_KVM_AMD_SEV
> @@ -125,13 +121,13 @@ static bool __sev_recycle_asids(int min_asid, int max_asid)
>
> static int sev_misc_cg_try_charge(struct kvm_sev_info *sev)
> {
> - enum misc_res_type type = sev->es_active ? MISC_CG_RES_SEV_ES : MISC_CG_RES_SEV;
> + enum misc_res_type type = MISC_CG_RES_SEV;
> return misc_cg_try_charge(type, sev->misc_cg, 1);
> }
>
> static void sev_misc_cg_uncharge(struct kvm_sev_info *sev)
> {
> - enum misc_res_type type = sev->es_active ? MISC_CG_RES_SEV_ES : MISC_CG_RES_SEV;
> + enum misc_res_type type = MISC_CG_RES_SEV;
> misc_cg_uncharge(type, sev->misc_cg, 1);
> }
>
> @@ -2167,7 +2163,7 @@ void __init sev_set_cpu_caps(void)
> void __init sev_hardware_setup(void)
> {
> #ifdef CONFIG_KVM_AMD_SEV
> - unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
> + unsigned int eax, ebx, ecx, edx, sev_asid_count;
> bool sev_es_supported = false;
> bool sev_supported = false;
>
> @@ -2236,14 +2232,7 @@ void __init sev_hardware_setup(void)
> if (!boot_cpu_has(X86_FEATURE_SEV_ES))
> goto out;
>
> - /* Has the system been allocated ASIDs for SEV-ES? */
> - if (min_sev_asid == 1)
> - goto out;
> -
> - sev_es_asid_count = min_sev_asid - 1;
> - WARN_ON_ONCE(misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count));
> sev_es_supported = true;
> -
> out:
> if (boot_cpu_has(X86_FEATURE_SEV))
> pr_info("SEV %s (ASIDs %u - %u)\n",
> @@ -2271,7 +2260,6 @@ void sev_hardware_unsetup(void)
> bitmap_free(sev_reclaim_asid_bitmap);
>
> misc_cg_set_capacity(MISC_CG_RES_SEV, 0);
> - misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0);
> }
>
> int sev_cpu_init(struct svm_cpu_data *sd)
> diff --git a/include/linux/misc_cgroup.h b/include/linux/misc_cgroup.h
> index c238207d1615..23d3cd153f60 100644
> --- a/include/linux/misc_cgroup.h
> +++ b/include/linux/misc_cgroup.h
> @@ -15,8 +15,6 @@ enum misc_res_type {
> #ifdef CONFIG_KVM_AMD_SEV
> /* AMD SEV ASIDs resource */
> MISC_CG_RES_SEV,
> - /* AMD SEV-ES ASIDs resource */
> - MISC_CG_RES_SEV_ES,
> #endif
> MISC_CG_RES_TYPES
> };
> --

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