From: Tom Lendacky <thomas.lendacky@amd.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Brijesh Singh <brijesh.singh@amd.com>
Subject: Re: [RFC PATCH 08/35] KVM: SVM: Prevent debugging under SEV-ES
Date: Wed, 16 Sep 2020 10:11:10 -0500 [thread overview]
Message-ID: <5e816811-450f-b732-76f7-6130479642e0@amd.com> (raw)
In-Reply-To: <aff46d8d-07ff-7d14-3e7f-ffe60f2bd779@amd.com>
On 9/15/20 3:13 PM, Tom Lendacky wrote:
> On 9/15/20 11:30 AM, Sean Christopherson wrote:
>> On Tue, Sep 15, 2020 at 08:37:12AM -0500, Tom Lendacky wrote:
>>> On 9/14/20 4:26 PM, Sean Christopherson wrote:
>>>> On Mon, Sep 14, 2020 at 03:15:22PM -0500, Tom Lendacky wrote:
>>>>> From: Tom Lendacky <thomas.lendacky@amd.com>
>>>>>
>>>>> Since the guest register state of an SEV-ES guest is encrypted, debugging
>>>>> is not supported. Update the code to prevent guest debugging when the
>>>>> guest is an SEV-ES guest. This includes adding a callable function that
>>>>> is used to determine if the guest supports being debugged.
>>>>>
>>>>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>>>>> ---
>>>>> arch/x86/include/asm/kvm_host.h | 2 ++
>>>>> arch/x86/kvm/svm/svm.c | 16 ++++++++++++++++
>>>>> arch/x86/kvm/vmx/vmx.c | 7 +++++++
>>>>> arch/x86/kvm/x86.c | 3 +++
>>>>> 4 files changed, 28 insertions(+)
>>>>>
>>>>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>>>>> index c900992701d6..3e2a3d2a8ba8 100644
>>>>> --- a/arch/x86/include/asm/kvm_host.h
>>>>> +++ b/arch/x86/include/asm/kvm_host.h
>>>>> @@ -1234,6 +1234,8 @@ struct kvm_x86_ops {
>>>>> void (*reg_read_override)(struct kvm_vcpu *vcpu, enum kvm_reg reg);
>>>>> void (*reg_write_override)(struct kvm_vcpu *vcpu, enum kvm_reg reg,
>>>>> unsigned long val);
>>>>> +
>>>>> + bool (*allow_debug)(struct kvm *kvm);
>>>>
>>>> Why add both allow_debug() and vmsa_encrypted? I assume there are scenarios
>>>> where allow_debug() != vmsa_encrypted? E.g. is there a debug mode for SEV-ES
>>>> where the VMSA is not encrypted, but KVM (ironically) can't intercept #DBs or
>>>> something?
>>>
>>> No, once the guest has had LAUNCH_UPDATE_VMSA run against the vCPUs, then
>>> the vCPU states are all encrypted. But that doesn't mean that debugging
>>> can't be done in the future.
>>
>> I don't quite follow the "doesn't mean debugging can't be done in the future".
>> Does that imply that debugging could be supported for SEV-ES guests, even if
>> they have an encrypted VMSA?
>
> Almost anything can be done with software. It would require a lot of
> hypervisor and guest code and changes to the GHCB spec, etc. So given
> that, probably just the check for arch.guest_state_protected is enough for
> now. I'll just need to be sure none of the debugging paths can be taken
> before the VMSA is encrypted.
So I don't think there's any guarantee that the KVM_SET_GUEST_DEBUG ioctl
couldn't be called before the VMSA is encrypted, meaning I can't check the
arch.guest_state_protected bit for that call. So if we really want to get
rid of the allow_debug() op, I'd need some other way to indicate that this
is an SEV-ES / protected state guest.
How are you planning on blocking this ioctl for TDX? Would the
arch.guest_state_protected bit be sit earlier than is done for SEV-ES?
Thanks,
Tom
>
> Thanks,
> Tom
>
>>
next prev parent reply other threads:[~2020-09-16 20:52 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 20:15 [RFC PATCH 00/35] SEV-ES hypervisor support Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 01/35] KVM: SVM: Remove the call to sev_platform_status() during setup Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 02/35] KVM: SVM: Add support for SEV-ES capability in KVM Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 03/35] KVM: SVM: Add indirect access to the VM save area Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 04/35] KVM: SVM: Make GHCB accessor functions available to the hypervisor Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 05/35] KVM: SVM: Add initial support for SEV-ES GHCB access to KVM Tom Lendacky
[not found] ` <20200914205801.GA7084@sjchrist-ice>
2020-09-15 13:24 ` Tom Lendacky
2020-09-15 16:28 ` Sean Christopherson
2020-09-16 14:54 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 06/35] KVM: SVM: Add required changes to support intercepts under SEV-ES Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 07/35] KVM: SVM: Modify DRx register intercepts for an SEV-ES guest Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 08/35] KVM: SVM: Prevent debugging under SEV-ES Tom Lendacky
2020-09-14 21:26 ` Sean Christopherson
2020-09-15 13:37 ` Tom Lendacky
2020-09-15 16:30 ` Sean Christopherson
2020-09-15 20:13 ` Tom Lendacky
2020-09-16 15:11 ` Tom Lendacky [this message]
2020-09-16 16:02 ` Sean Christopherson
2020-09-16 16:38 ` Tom Lendacky
2020-09-16 16:49 ` Sean Christopherson
2020-09-16 20:27 ` Tom Lendacky
2020-09-16 22:50 ` Sean Christopherson
2020-09-17 16:27 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 09/35] KVM: SVM: Do not emulate MMIO " Tom Lendacky
2020-09-14 21:33 ` Sean Christopherson
2020-09-15 13:38 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 10/35] KVM: SVM: Cannot re-initialize the VMCB after shutdown with SEV-ES Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 11/35] KVM: SVM: Prepare for SEV-ES exit handling in the sev.c file Tom Lendacky
[not found] ` <20200915172148.GE8420@sjchrist-ice>
2020-09-16 16:22 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 12/35] KVM: SVM: Add initial support for a VMGEXIT VMEXIT Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 13/35] KVM: SVM: Create trace events for VMGEXIT processing Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 14/35] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x002 Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 15/35] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x004 Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 16/35] KVM: SVM: Add support for SEV-ES GHCB MSR protocol function 0x100 Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 17/35] KVM: SVM: Create trace events for VMGEXIT MSR protocol processing Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 18/35] KVM: SVM: Support MMIO for an SEV-ES guest Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 19/35] KVM: SVM: Support port IO operations " Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 20/35] KVM: SVM: Add SEV/SEV-ES support for intercepting INVD Tom Lendacky
2020-09-14 22:00 ` Sean Christopherson
2020-09-15 15:08 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 21/35] KVM: SVM: Add support for EFER write traps for an SEV-ES guest Tom Lendacky
[not found] ` <20200914220800.GI7192@sjchrist-ice>
2020-09-15 15:45 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 22/35] KVM: SVM: Add support for CR0 " Tom Lendacky
2020-09-14 22:13 ` Sean Christopherson
2020-09-15 15:56 ` Tom Lendacky
2020-11-30 18:15 ` Paolo Bonzini
2020-09-14 20:15 ` [RFC PATCH 23/35] KVM: SVM: Add support for CR4 " Tom Lendacky
2020-09-14 22:16 ` Sean Christopherson
2020-11-30 18:16 ` Paolo Bonzini
2020-09-14 20:15 ` [RFC PATCH 24/35] KVM: SVM: Add support for CR8 " Tom Lendacky
2020-09-14 22:19 ` Sean Christopherson
2020-09-15 15:57 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 25/35] KVM: x86: Update __get_sregs() / __set_sregs() to support SEV-ES Tom Lendacky
2020-09-14 21:37 ` Sean Christopherson
2020-09-15 14:19 ` Tom Lendacky
2020-09-15 16:33 ` Sean Christopherson
2020-09-15 20:37 ` Tom Lendacky
2020-09-15 22:44 ` Sean Christopherson
2020-11-30 18:28 ` Paolo Bonzini
2020-11-30 19:39 ` Sean Christopherson
2020-09-14 20:15 ` [RFC PATCH 26/35] KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest Tom Lendacky
[not found] ` <20200914213917.GD7192@sjchrist-ice>
2020-09-15 14:25 ` Tom Lendacky
2020-09-15 16:34 ` Sean Christopherson
2020-09-14 20:15 ` [RFC PATCH 27/35] KVM: SVM: Add support for booting APs for an " Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 28/35] KVM: X86: Update kvm_skip_emulated_instruction() " Tom Lendacky
2020-09-14 21:51 ` Sean Christopherson
2020-09-15 14:57 ` Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 29/35] KVM: SVM: Add NMI support " Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 30/35] KVM: SVM: Set the encryption mask for the SVM host save area Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 31/35] KVM: SVM: Update ASID allocation to support SEV-ES guests Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 32/35] KVM: SVM: Provide support for SEV-ES vCPU creation/loading Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 33/35] KVM: SVM: Provide support for SEV-ES vCPU loading Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 34/35] KVM: SVM: Provide an updated VMRUN invocation for SEV-ES guests Tom Lendacky
2020-09-14 20:15 ` [RFC PATCH 35/35] KVM: SVM: Provide support to launch and run an SEV-ES guest Tom Lendacky
2020-09-14 22:59 ` [RFC PATCH 00/35] SEV-ES hypervisor support Sean Christopherson
2020-09-15 17:22 ` Tom Lendacky
2020-09-15 17:32 ` Sean Christopherson
2020-09-15 20:05 ` Brijesh Singh
2020-09-16 0:19 ` Sean Christopherson
2020-10-13 20:26 ` Tom Lendacky
2020-11-30 15:31 ` Paolo Bonzini
2020-11-30 16:06 ` Tom Lendacky
2020-11-30 18:18 ` Sean Christopherson
2020-11-30 18:14 ` Sean Christopherson
2020-11-30 18:35 ` Paolo Bonzini
2020-11-30 19:35 ` Sean Christopherson
2020-11-30 20:24 ` Paolo Bonzini
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