From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com,
joro@8bytes.org, bgardon@google.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kvm: x86/mmu: Use cpuid to determine max gfn
Date: Fri, 4 Dec 2020 09:48:58 +0100 [thread overview]
Message-ID: <9f527b7b-96de-6657-aa48-8de401f5083e@redhat.com> (raw)
In-Reply-To: <X8mGSoB6KCiFsJdC@google.com>
On 04/12/20 01:43, Sean Christopherson wrote:
> On Thu, Dec 03, 2020, Rick Edgecombe wrote:
>> In the TDP MMU, use shadow_phys_bits to dermine the maximum possible GFN
>> mapped in the guest for zapping operations. boot_cpu_data.x86_phys_bits
>> may be reduced in the case of HW features that steal HPA bits for other
>> purposes. However, this doesn't necessarily reduce GPA space that can be
>> accessed via TDP. So zap based on a maximum gfn calculated with MAXPHYADDR
>> retrieved from CPUID. This is already stored in shadow_phys_bits, so use
>> it instead of x86_phys_bits.
>>
>> Fixes: faaf05b00aec ("kvm: x86/mmu: Support zapping SPTEs in the TDP MMU")
>> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
>
> Dang, in hindsight it'd be nice if KVM_CAP_SMALLER_MAXPHYADDR allowed explicitly
> setting the max MAXPHYADDR for an entire VM instead of being a simple toggle.
> E.g. TDX and SEV-ES likely could also make use of "what's this VM's max GPA?".
>
> Reviewed-by: Sean Christopherson <seanjc@google.com>
>
Queued, thanks.
Paolo
prev parent reply other threads:[~2020-12-04 8:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-03 23:11 [PATCH] kvm: x86/mmu: Use cpuid to determine max gfn Rick Edgecombe
2020-12-04 0:43 ` Sean Christopherson
2020-12-04 8:48 ` Paolo Bonzini [this message]
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