From: Yu Zhang <yu.c.zhang@linux.intel.com>
To: Robert Hoo <robert.hu@linux.intel.com>
Cc: Yuan Yao <yuan.yao@linux.intel.com>,
pbonzini@redhat.com, seanjc@google.com,
kirill.shutemov@linux.intel.com, kvm@vger.kernel.org,
Jingqi Liu <jingqi.liu@intel.com>
Subject: Re: [PATCH v3 6/9] KVM: x86: Untag LAM bits when applicable
Date: Wed, 21 Dec 2022 18:10:32 +0800 [thread overview]
Message-ID: <20221221101032.3g54omjqhnscuaqw@linux.intel.com> (raw)
In-Reply-To: <ec96c8499a9a48aea59ce87f0244c9b31f91641f.camel@linux.intel.com>
On Wed, Dec 21, 2022 at 04:49:26PM +0800, Robert Hoo wrote:
> On Wed, 2022-12-21 at 16:02 +0800, Yu Zhang wrote:
> > > Emm, I take a look at the callers, looks like they're segment
> > > registers
> > > and MSRs. Per spec (ISE 10.4): processors that support LAM continue
> > > to
> > > require the addresses written to control registers or MSRs be
> > > legacy
> > > canonical. So, like the handling on your last commented point on
> > > this
> > > patch, such situation needs no changes, i.e. legacy canonical still
> > > applied.
> > >
> >
> > Well, it's not about the control register or MSR emulation. It is
> > about
> > the instruction decoder, which may encounter an instruction with a
> > memory
> > operand with LAM bits occupied.
> >
> OK, combine reply to you and Yuan's comments here.
> So you're talking about when KVM emulates an instruction, and that
> instruction is accessing memory, and the address for the memory can be
> LAM tagged.
> I think instruction emulation and memory access should be separated,
> and LAM rules should apply to memory access phase. But frankly
> speaking, I haven't looked into such case yet. Can you name an example
> of such emulated instruction? I can take a look, hoping that the
> emulation accessing memory falls into same code path as page fault
> handling.
I do not know the usage case of LAM. According to the spec, LAM does
not apply to instruction fetches, so guest rip and target addresses
in instructions such as jump, call etc. do not need special treatment.
But the spec does not say if LAM can be used to MMIO addresses...
B.R.
Yu
next prev parent reply other threads:[~2022-12-21 10:15 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
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 [this message]
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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