From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Vineeth Pillai <viremana@linux.microsoft.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"K. Y. Srinivasan" <kys@microsoft.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
Lan Tianyu <Tianyu.Lan@microsoft.com>,
Michael Kelley <mikelley@microsoft.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Wei Liu <wei.liu@kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>
Subject: Re: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM
Date: Thu, 08 Apr 2021 13:06:53 +0200 [thread overview]
Message-ID: <87lf9tavci.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <e14dac75ff1088b2c4bea361954b37e414edd03c.1617804573.git.viremana@linux.microsoft.com>
Vineeth Pillai <viremana@linux.microsoft.com> writes:
> Detect nested features exposed by Hyper-V if SVM is enabled.
>
> Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
> ---
> arch/x86/kernel/cpu/mshyperv.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 3546d3e21787..4d364acfe95d 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -325,9 +325,17 @@ static void __init ms_hyperv_init_platform(void)
> ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
> }
>
> - if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
> + /*
> + * AMD does not need enlightened VMCS as VMCB is already a
> + * datastructure in memory.
Well, VMCS is also a structure in memory, isn't it? It's just that we
don't have a 'clean field' concept for it and we can't use normal memory
accesses.
> We need to get the nested
> + * features if SVM is enabled.
> + */
> + if (boot_cpu_has(X86_FEATURE_SVM) ||
> + ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
Do I understand correctly that we can just look at CPUID.0x40000000.EAX
and in case it is >= 0x4000000A we can read HYPERV_CPUID_NESTED_FEATURES
leaf? I'd suggest we do that intead then.
> ms_hyperv.nested_features =
> cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
> + pr_info("Hyper-V nested_features: 0x%x\n",
> + ms_hyperv.nested_features);
> }
>
> /*
--
Vitaly
next prev parent reply other threads:[~2021-04-08 11:07 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-07 14:41 [PATCH 0/7] Hyper-V nested virt enlightenments for SVM Vineeth Pillai
2021-04-07 14:41 ` [PATCH 1/7] hyperv: Detect Nested virtualization support " Vineeth Pillai
2021-04-07 16:09 ` Borislav Petkov
2021-04-07 19:55 ` Michael Kelley
2021-04-07 22:48 ` Sean Christopherson
2021-04-08 13:26 ` Vineeth Pillai
2021-04-08 11:06 ` Vitaly Kuznetsov [this message]
2021-04-08 13:15 ` Vineeth Pillai
2021-04-08 15:24 ` Sean Christopherson
2021-04-09 12:23 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 2/7] hyperv: SVM enlightened TLB flush support flag Vineeth Pillai
2021-04-07 19:56 ` Michael Kelley
2021-04-08 13:45 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 3/7] KVM: x86: hyper-v: Move the remote TLB flush logic out of vmx Vineeth Pillai
2021-04-08 11:14 ` Vitaly Kuznetsov
2021-04-08 13:18 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 4/7] KVM: SVM: hyper-v: Nested enlightenments in VMCB Vineeth Pillai
2021-04-08 15:44 ` Paolo Bonzini
2021-04-09 12:24 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 5/7] KVM: SVM: hyper-v: Remote TLB flush for SVM Vineeth Pillai
2021-04-08 11:18 ` Vitaly Kuznetsov
2021-04-08 13:19 ` Vineeth Pillai
2021-04-07 14:41 ` [PATCH 6/7] KVM: SVM: hyper-v: Enlightened MSR-Bitmap support Vineeth Pillai
2021-04-08 11:22 ` Vitaly Kuznetsov
2021-04-08 15:47 ` Paolo Bonzini
2021-04-07 14:41 ` [PATCH 7/7] KVM: SVM: hyper-v: Direct Virtual Flush support Vineeth Pillai
2021-04-08 11:25 ` Vitaly Kuznetsov
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