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From: Paolo Bonzini <pbonzini@redhat.com>
To: Wei Huang <wei.huang2@amd.com>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, vkuznets@redhat.com,
	mlevitsk@redhat.com, seanjc@google.com, joro@8bytes.org,
	bp@alien8.de, tglx@linutronix.de, mingo@redhat.com,
	x86@kernel.org, jmattson@google.com, wanpengli@tencent.com,
	bsd@redhat.com, dgilbert@redhat.com, luto@amacapital.net
Subject: Re: [PATCH v3 4/4] KVM: SVM: Support #GP handling for the case of nested on nested
Date: Tue, 26 Jan 2021 12:39:16 +0100	[thread overview]
Message-ID: <f3611af9-dce2-b07f-e5c4-5a47c7e519a6@redhat.com> (raw)
In-Reply-To: <20210126081831.570253-5-wei.huang2@amd.com>

On 26/01/21 09:18, Wei Huang wrote:
> Under the case of nested on nested (L0->L1->L2->L3), #GP triggered by 
> SVM instructions can be hided from L1. Instead the hypervisor can inject 
> the proper #VMEXIT to inform L1 of what is happening. Thus L1 can avoid 
> invoking the #GP workaround. For this reason we turns on guest VM's 
> X86_FEATURE_SVME_ADDR_CHK bit for KVM running inside VM to receive the 
> notification and change behavior.

Slightly reworked commit message:

KVM: SVM: Fix #GP handling for doubly-nested virtualization

Under the case of nested on nested (L0, L1, L2 are all hypervisors),
#GP triggered by SVM instructions can be hidden from L1.  Because
we do not support emulation of the vVMLOAD/VMSAVE feature, the
L0 hypervisor can inject the proper #VMEXIT to inform L1 of what is
happening and L1 can avoid invoking the #GP workaround.

Thanks,

Paolo


  reply	other threads:[~2021-01-26 11:51 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-26  8:18 [PATCH v3 0/4] Handle #GP for SVM execution instructions Wei Huang
2021-01-26  8:18 ` [PATCH v3 1/4] KVM: x86: Factor out x86 instruction emulation with decoding Wei Huang
2021-01-26  8:18 ` [PATCH v3 2/4] KVM: SVM: Add emulation support for #GP triggered by SVM instructions Wei Huang
2021-01-26 11:34   ` Paolo Bonzini
2021-01-26 11:50   ` Maxim Levitsky
2021-01-26  8:18 ` [PATCH v3 3/4] KVM: SVM: Add support for SVM instruction address check change Wei Huang
2021-01-26 11:52   ` Maxim Levitsky
2021-01-26 15:39     ` Wei Huang
2021-01-26  8:18 ` [PATCH v3 4/4] KVM: SVM: Support #GP handling for the case of nested on nested Wei Huang
2021-01-26 11:39   ` Paolo Bonzini [this message]
2021-01-26 11:59   ` Maxim Levitsky
2021-01-26 11:39 ` [PATCH v3 0/4] Handle #GP for SVM execution instructions Paolo Bonzini
2021-01-26 15:05   ` Wei Huang

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