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SubjectRe: [Part2 PATCH v5 15/31] KVM: SVM: Reserve ASID range for SEV guest
On Wed, Oct 04, 2017 at 08:13:56AM -0500, Brijesh Singh wrote:
> A SEV-enabled guest must use ASIDs from the defined subset, while non-SEV
> guests can use the remaining ASID range. The range of allowed SEV guest
> ASIDs is [1 - CPUID_8000_001F[ECX][31:0]].
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: x86@kernel.org
> Cc: kvm@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
> arch/x86/kvm/svm.c | 23 ++++++++++++++++++++++-
> 1 file changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index be2e98c01b22..3244b8f88010 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -323,6 +323,8 @@ enum {
>
> #define VMCB_AVIC_APIC_BAR_MASK 0xFFFFFFFFFF000ULL
>
> +static unsigned int max_sev_asid;
> +
> static inline void mark_all_dirty(struct vmcb *vmcb)
> {
> vmcb->control.clean = 0;
> @@ -787,7 +789,7 @@ static int svm_hardware_enable(void)
> sd->asid_generation = 1;
> sd->max_asid = cpuid_ebx(SVM_CPUID_FUNC) - 1;
> sd->next_asid = sd->max_asid + 1;
> - sd->min_asid = 1;
> + sd->min_asid = max_sev_asid + 1;
>
> gdt = get_current_gdt_rw();
> sd->tss_desc = (struct kvm_ldttss_desc *)(gdt + GDT_ENTRY_TSS);
> @@ -1054,6 +1056,15 @@ static int avic_ga_log_notifier(u32 ga_tag)
> return 0;
> }
>
> +/*
> + * Get maximum number of encrypted guest supported: Fn8001_001F[ECX].
> + * [31:0]: Number of supported guest
> + */
> +static __init void sev_hardware_setup(void)
> +{
> + max_sev_asid = cpuid_ecx(0x8000001F);
> +}
> +
> static __init int svm_hardware_setup(void)
> {
> int cpu;
> @@ -1084,6 +1095,16 @@ static __init int svm_hardware_setup(void)
> kvm_tsc_scaling_ratio_frac_bits = 32;
> }
>
> + if (sev) {
> + if (!boot_cpu_has(X86_FEATURE_SEV) ||
> + !IS_ENABLED(CONFIG_KVM_AMD_SEV)) {
> + sev = false;
> + } else {
> + sev_hardware_setup();
> + pr_info("SEV supported\n");
> + }
> + }

Flip that logic:

---
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 3244b8f88010..d4b62536e305 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1057,8 +1057,8 @@ static int avic_ga_log_notifier(u32 ga_tag)
}

/*
- * Get maximum number of encrypted guest supported: Fn8001_001F[ECX].
- * [31:0]: Number of supported guest
+ * Get the maximum number of encrypted guests:
+ * Fn8001_001F[ECX][31:0]: Number of supported guests.
*/
static __init void sev_hardware_setup(void)
{
@@ -1096,12 +1096,12 @@ static __init int svm_hardware_setup(void)
}

if (sev) {
- if (!boot_cpu_has(X86_FEATURE_SEV) ||
- !IS_ENABLED(CONFIG_KVM_AMD_SEV)) {
- sev = false;
- } else {
+ if (boot_cpu_has(X86_FEATURE_SEV) &&
+ IS_ENABLED(CONFIG_KVM_AMD_SEV)) {
sev_hardware_setup();
pr_info("SEV supported\n");
+ } else {
+ sev = false;
}
}

--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.

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