From: Sean Christopherson <seanjc@google.com>
To: Robert Hoo <robert.hu@linux.intel.com>
Cc: pbonzini@redhat.com, kirill.shutemov@linux.intel.com,
kvm@vger.kernel.org, Jingqi Liu <jingqi.liu@intel.com>
Subject: Re: [PATCH v3 2/9] KVM: x86: Add CR4.LAM_SUP in guest owned bits
Date: Mon, 9 Jan 2023 16:29:27 +0000 [thread overview]
Message-ID: <Y7xA53sLxCwzfvgD@google.com> (raw)
In-Reply-To: <5f2f0a44fbb1a2eab36183dfc2fcaf53e1109793.camel@linux.intel.com>
On Sat, Jan 07, 2023, Robert Hoo wrote:
> On Sat, 2023-01-07 at 00:38 +0000, Sean Christopherson wrote:
> > On Fri, Dec 09, 2022, Robert Hoo wrote:
> > > If LAM enabled, CR4.LAM_SUP is owned by guest; otherwise, reserved.
> >
> > Why is it passed through to the guest?
>
> I think no need to intercept guest's control over CR4.LAM_SUP, which
> controls LAM appliance to supervisor mode address.
That's not a sufficient justification. KVM doesn't strictly need to intercept
most CR4 bits, but not intercepting has performance implications, e.g. KVM needs
to do a VMREAD(GUEST_CR4) to get LAM_SUP if the bit is pass through. As a base
rule, KVM intercepts CR4 bits unless there's a reason not to, e.g. if the CR4 bit
in question is written frequently by real guests and/or never consumed by KVM.
next prev parent reply other threads:[~2023-01-09 16:30 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-09 4:45 [PATCH v3 0/9] Linear Address Masking (LAM) KVM Enabling Robert Hoo
2022-12-09 4:45 ` [PATCH v3 1/9] KVM: x86: Rename cr4_reserved/rsvd_* variables to be more readable Robert Hoo
2022-12-28 3:37 ` Binbin Wu
2022-12-29 1:42 ` Robert Hoo
2023-01-07 0:35 ` Sean Christopherson
2023-01-07 13:30 ` Robert Hoo
2023-01-08 14:18 ` Xiaoyao Li
2023-01-09 3:07 ` Robert Hoo
2022-12-09 4:45 ` [PATCH v3 2/9] KVM: x86: Add CR4.LAM_SUP in guest owned bits Robert Hoo
2023-01-07 0:38 ` Sean Christopherson
2023-01-07 13:32 ` Robert Hoo
2023-01-09 16:29 ` Sean Christopherson [this message]
2023-01-10 3:56 ` Robert Hoo
2023-01-11 17:35 ` Sean Christopherson
2022-12-09 4:45 ` [PATCH v3 3/9] KVM: x86: MMU: Rename get_cr3() --> get_pgd() and clear high bits for pgd Robert Hoo
2022-12-19 6:44 ` Yuan Yao
2022-12-20 14:07 ` Robert Hoo
2023-01-07 0:45 ` Sean Christopherson
2023-01-07 13:36 ` Robert Hoo
2022-12-09 4:45 ` [PATCH v3 4/9] KVM: x86: MMU: Commets update Robert Hoo
2022-12-09 4:45 ` [PATCH v3 5/9] KVM: x86: MMU: Integrate LAM bits when build guest CR3 Robert Hoo
2022-12-19 6:53 ` Yuan Yao
2022-12-20 14:07 ` Robert Hoo
2022-12-21 2:12 ` Yuan Yao
2022-12-21 7:50 ` Yu Zhang
2022-12-21 8:55 ` Robert Hoo
2022-12-09 4:45 ` [PATCH v3 6/9] KVM: x86: Untag LAM bits when applicable Robert Hoo
2022-12-19 7:32 ` Yuan Yao
2022-12-20 14:07 ` Robert Hoo
2022-12-19 9:45 ` Yuan Yao
2022-12-20 14:07 ` Robert Hoo
2022-12-21 2:38 ` Yuan Yao
2022-12-21 8:02 ` Yu Zhang
2022-12-21 8:49 ` Robert Hoo
2022-12-21 10:10 ` Yu Zhang
2022-12-21 10:30 ` Yuan Yao
2022-12-21 12:40 ` Yu Zhang
2022-12-22 8:21 ` Yu Zhang
2022-12-23 2:36 ` Yuan Yao
2022-12-23 3:55 ` Robert Hoo
2022-12-21 0:35 ` Yang, Weijiang
2022-12-21 1:38 ` Robert Hoo
2022-12-21 2:55 ` Yuan Yao
2022-12-21 8:22 ` Robert Hoo
2022-12-21 9:35 ` Yuan Yao
2022-12-21 10:22 ` Yu Zhang
2022-12-21 10:33 ` Yuan Yao
2022-12-21 8:14 ` Yu Zhang
2022-12-21 8:37 ` Yu Zhang
2022-12-28 8:32 ` Binbin Wu
2022-12-29 0:41 ` Robert Hoo
2022-12-09 4:45 ` [PATCH v3 7/9] KVM: x86: When judging setting CR3 valid or not, consider LAM bits Robert Hoo
2022-12-09 4:45 ` [PATCH v3 8/9] KVM: x86: When guest set CR3, handle LAM bits semantics Robert Hoo
2022-12-20 9:10 ` Liu, Jingqi
2022-12-20 14:16 ` Robert Hoo
2022-12-21 8:30 ` Yu Zhang
2022-12-21 12:52 ` Robert Hoo
2022-12-09 4:45 ` [PATCH v3 9/9] KVM: x86: LAM: Expose LAM CPUID to user space VMM Robert Hoo
2022-12-19 6:12 ` [PATCH v3 0/9] Linear Address Masking (LAM) KVM Enabling Robert Hoo
2022-12-19 8:09 ` Yuan Yao
2022-12-20 14:06 ` Robert Hoo
2022-12-20 9:20 ` Liu, Jingqi
2022-12-20 14:19 ` Robert Hoo
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