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From: Santosh Shukla <santosh.shukla@amd.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Tom Lendacky <thomas.lendacky@amd.com>, <kvm@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <Santosh.Shukla@amd.com>
Subject: [PATCH 0/7] Virtual NMI feature
Date: Thu, 2 Jun 2022 19:56:13 +0530	[thread overview]
Message-ID: <20220602142620.3196-1-santosh.shukla@amd.com> (raw)

Currently, NMI is delivered to the guest using the Event Injection
mechanism [1]. The Event Injection mechanism does not block the delivery
of subsequent NMIs. So the Hypervisor needs to track the NMI delivery
and its completion(by intercepting IRET) before sending a new NMI.

Virtual NMI (VNMI) allows the hypervisor to inject the NMI into the guest
w/o using Event Injection mechanism meaning not required to track the
guest NMI and intercepting the IRET. To achieve that,
VNMI feature provides virtualized NMI and NMI_MASK capability bits in
VMCB intr_control -
V_NMI(11) - Indicates whether a virtual NMI is pending in the guest.
V_NMI_MASK(12) - Indicates whether virtual NMI is masked in the guest.
V_NMI_ENABLE(26) - Enables the NMI virtualization feature for the guest.

When Hypervisor wants to inject NMI, it will set V_NMI bit, Processor will
clear the V_NMI bit and Set the V_NMI_MASK which means the Guest is
handling NMI, After the guest handled the NMI, The processor will clear
the V_NMI_MASK on the successful completion of IRET instruction
Or if VMEXIT occurs while delivering the virtual NMI.

To enable the VNMI capability, Hypervisor need to program
V_NMI_ENABLE bit 1.

The presence of this feature is indicated via the CPUID function
0x8000000A_EDX[25].

Testing -
* Used qemu's `inject_nmi` for testing.
* tested with and w/o AVIC case.
* tested with kvm-unit-test

Thanks,
Santosh
[1] https://www.amd.com/system/files/TechDocs/40332.pdf - APM Vol2,
ch-15.20 - "Event Injection".

Santosh Shukla (7):
  x86/cpu: Add CPUID feature bit for VNMI
  KVM: SVM: Add VNMI bit definition
  KVM: SVM: Add VNMI support in get/set_nmi_mask
  KVM: SVM: Report NMI not allowed when Guest busy handling VNMI
  KVM: SVM: Add VNMI support in inject_nmi
  KVM: nSVM: implement nested VNMI
  KVM: SVM: Enable VNMI feature

 arch/x86/include/asm/cpufeatures.h |  1 +
 arch/x86/include/asm/svm.h         |  7 +++++
 arch/x86/kvm/svm/nested.c          |  8 +++++
 arch/x86/kvm/svm/svm.c             | 47 ++++++++++++++++++++++++++++--
 arch/x86/kvm/svm/svm.h             |  1 +
 5 files changed, 62 insertions(+), 2 deletions(-)

-- 
2.25.1


             reply	other threads:[~2022-06-02 14:26 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-02 14:26 Santosh Shukla [this message]
2022-06-02 14:26 ` [PATCH 1/7] x86/cpu: Add CPUID feature bit for VNMI Santosh Shukla
2022-06-07 12:32   ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 2/7] KVM: SVM: Add VNMI bit definition Santosh Shukla
2022-06-07 12:55   ` Maxim Levitsky
2022-06-17 14:42     ` Shukla, Santosh
2022-06-02 14:26 ` [PATCH 3/7] KVM: SVM: Add VNMI support in get/set_nmi_mask Santosh Shukla
2022-06-07 13:07   ` Maxim Levitsky
2022-06-17 14:45     ` Shukla, Santosh
2022-06-17 14:48       ` Shukla, Santosh
2022-07-10 16:09         ` Maxim Levitsky
2022-07-21  9:25           ` Shukla, Santosh
2022-07-10 18:39         ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 4/7] KVM: SVM: Report NMI not allowed when Guest busy handling VNMI Santosh Shukla
2022-06-07 13:10   ` Maxim Levitsky
2022-06-07 13:12     ` Maxim Levitsky
2022-06-17 14:59       ` Shukla, Santosh
2022-07-10 16:08         ` Maxim Levitsky
2022-07-21  9:31           ` Shukla, Santosh
2022-07-21 11:56             ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 5/7] KVM: SVM: Add VNMI support in inject_nmi Santosh Shukla
2022-06-07 13:14   ` Maxim Levitsky
2022-06-17 15:05     ` Shukla, Santosh
2022-07-10 16:07       ` Maxim Levitsky
2022-06-02 14:26 ` [PATCH 6/7] KVM: nSVM: implement nested VNMI Santosh Shukla
2022-06-07 13:22   ` Maxim Levitsky
2022-06-17 15:08     ` Shukla, Santosh
2022-06-02 14:26 ` [PATCH 7/7] KVM: SVM: Enable VNMI feature Santosh Shukla
2022-06-06 23:01 ` [PATCH 0/7] Virtual NMI feature Jim Mattson
2022-06-08  8:23   ` Shukla, Santosh

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