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From: Wei Huang <wei.huang2@amd.com>
To: Maxim Levitsky <mlevitsk@redhat.com>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, pbonzini@redhat.com,
	vkuznets@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
Subject: Re: [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions
Date: Tue, 12 Jan 2021 15:05:34 -0600	[thread overview]
Message-ID: <d6c3f238-9f63-fc80-1866-bbb685ce044a@amd.com> (raw)
In-Reply-To: <f95acfbbff46109092881874c8c78edcf58a72e8.camel@redhat.com>



On 1/12/21 5:09 AM, Maxim Levitsky wrote:
> On Tue, 2021-01-12 at 00:37 -0600, Wei Huang wrote:
>> From: Bandan Das <bsd@redhat.com>
>>
>> While running VM related instructions (VMRUN/VMSAVE/VMLOAD), some AMD
>> CPUs check EAX against reserved memory regions (e.g. SMM memory on host)
>> before checking VMCB's instruction intercept. If EAX falls into such
>> memory areas, #GP is triggered before VMEXIT. This causes problem under
>> nested virtualization. To solve this problem, KVM needs to trap #GP and
>> check the instructions triggering #GP. For VM execution instructions,
>> KVM emulates these instructions; otherwise it re-injects #GP back to
>> guest VMs.
>>
>> Signed-off-by: Bandan Das <bsd@redhat.com>
>> Co-developed-by: Wei Huang <wei.huang2@amd.com>
>> Signed-off-by: Wei Huang <wei.huang2@amd.com>
> 
> This is the ultimate fix for this bug that I had in mind,
> but I didn't dare to develop it, thinking it won't be accepted
> due to the added complexity.
> 
>  From a cursory look this look all right, and I will review
> and test this either today or tomorrow.

My tests mainly relied on the kvm-unit-test you developed (thanks BTW), 
on machines w/ and w/o CPUID_0x8000000A_EDX[28]=1. Both cases passed.

>

  reply	other threads:[~2021-01-12 21:50 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-12  6:37 [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Wei Huang
2021-01-12  6:37 ` [PATCH 2/2] KVM: SVM: Add support for VMCB address check change Wei Huang
2021-01-12 19:18   ` Sean Christopherson
2021-01-14 11:39     ` Maxim Levitsky
2021-01-14 12:04   ` Maxim Levitsky
2021-01-12 11:09 ` [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Maxim Levitsky
2021-01-12 21:05   ` Wei Huang [this message]
2021-01-12 12:15 ` Vitaly Kuznetsov
2021-01-12 15:11   ` Andy Lutomirski
2021-01-12 15:17     ` Maxim Levitsky
2021-01-12 15:22       ` Andy Lutomirski
2021-01-12 15:46         ` Bandan Das
2021-01-12 15:51           ` Andy Lutomirski
2021-01-12 17:56             ` Sean Christopherson
2021-01-13  4:55               ` Wei Huang
2021-01-12 21:50   ` Wei Huang
2021-01-12 14:01 ` Paolo Bonzini
2021-01-12 17:42   ` Sean Christopherson
2021-01-13 12:35     ` Paolo Bonzini
2021-01-15  7:00   ` Wei Huang
2021-01-17 18:20     ` Paolo Bonzini
2021-01-12 17:36 ` Sean Christopherson
2021-01-12 17:59   ` Sean Christopherson
2021-01-12 18:58     ` Andy Lutomirski
2021-01-13  5:15       ` Wei Huang
2021-01-14 11:42         ` Maxim Levitsky
2021-01-13  5:03     ` Wei Huang
2021-01-13 12:40     ` Paolo Bonzini
2021-01-12 19:40 ` Sean Christopherson
2021-01-12 20:00   ` Bandan Das
2021-01-14 11:47     ` Maxim Levitsky
2021-01-14 17:19       ` Sean Christopherson
2021-01-14 11:55 ` Maxim Levitsky

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