From: Sohil Mehta <sohil.mehta@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: "Chang S. Bae" <chang.seok.bae@intel.com>, <kvm@vger.kernel.org>,
<x86@kernel.org>, Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H . Peter Anvin" <hpa@zytor.com>, Shuah Khan <shuah@kernel.org>,
Binbin Wu <binbin.wu@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Kai Huang <kai.huang@intel.com>,
Fuad Tabba <fuad.tabba@linux.dev>, Chao Gao <chao.gao@intel.com>,
Yosry Ahmed <yosry@kernel.org>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
David Matlack <dmatlack@google.com>,
Bala-Vignesh-Reddy <reddybalavignesh9979@gmail.com>,
Kishen Maloor <kishen.maloor@intel.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
<linux-kernel@vger.kernel.org>, <linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH v4 4/7] KVM: VMX: Implement LASS violation check
Date: Tue, 15 Sep 2026 17:12:46 -0700 [thread overview]
Message-ID: <f4fdef08-fdf0-4af8-bf59-07c48625b282@intel.com> (raw)
In-Reply-To: <aqlQgQgnLDf2CHqx@google.com>
On 9/15/2026 7:04 AM, Sean Christopherson wrote:
> That said, I love Sohil's idea of adding a function comment. Someting along the
> lines of "The basic flow is this: <example>, but the actual behavior is far more
> subtle due to many exceptions and edge cases".
Great, how about this?
> /*
> * Check if an access violates LASS purely based on bit 63 of the linear address
> * and whether the access targets the "wrong" half of the address space. The
> * basic flow is straightforward:
> *
> * if (exempt from LASS)
> * no violation;
> * else if (user access)
> * violation when address is in the supervisor half;
> * else
> * violation when address is in the user half;
> *
> * but the actual behavior is far more subtle due to the many exceptions and
> * edge cases. For example, the implementation depends on which accesses are
> * exempt, what constitutes a user access, and how supervisor data accesses
> * differ from instruction fetches.
> */
> bool vmx_is_lass_violation(struct kvm_vcpu *vcpu, gva_t gva,
> unsigned int size, unsigned int flags)
Sean, other than this, do you want to see any big change in the series?
The sashiko complains are false-positives. There are a couple of nits to
be addressed, and I need to change Binbin's SoBs into Reviewed-bys.
Otherwise, I think the series (1-5) is getting ready to be picked up.
next prev parent reply other threads:[~2026-09-16 0:13 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-06 1:15 [PATCH v4 0/7] KVM: x86: Add LASS virtualization support Sohil Mehta
2026-08-06 1:15 ` [PATCH v4 1/7] KVM: x86: Add an emulator flag to differentiate branch targets from fetches Sohil Mehta
2026-08-06 1:15 ` [PATCH v4 2/7] KVM: x86: Use linear_read_system() to read the TSS I/O bitmap Sohil Mehta
2026-08-19 3:19 ` Binbin Wu
2026-08-19 5:03 ` Sohil Mehta
2026-08-19 5:21 ` H. Peter Anvin
2026-08-19 5:26 ` Binbin Wu
2026-08-06 1:15 ` [PATCH v4 3/7] KVM: x86: Add LASS violation checks during instruction emulation Sohil Mehta
2026-08-19 5:58 ` Binbin Wu
2026-08-06 1:15 ` [PATCH v4 4/7] KVM: VMX: Implement LASS violation check Sohil Mehta
2026-08-19 8:49 ` Binbin Wu
2026-09-14 17:43 ` Chang S. Bae
2026-09-15 5:10 ` Sohil Mehta
2026-09-15 14:04 ` Sean Christopherson
2026-09-16 0:12 ` Sohil Mehta [this message]
2026-09-16 18:38 ` Sean Christopherson
2026-09-16 21:49 ` Sohil Mehta
2026-08-06 1:15 ` [PATCH v4 5/7] KVM: x86: Virtualize LASS and advertise support to userspace Sohil Mehta
2026-08-19 9:01 ` Binbin Wu
2026-08-06 1:15 ` [PATCH v4 6/7] KVM: selftests: Add coverage for LASS CPUID and CR4 handling Sohil Mehta
2026-08-20 6:01 ` Binbin Wu
2026-08-06 1:15 ` [PATCH v4 7/7] selftests/x86: Add a userspace test for LASS enforcement Sohil Mehta
2026-08-20 6:36 ` Binbin Wu
2026-09-15 3:22 ` Sohil Mehta
2026-09-14 18:21 ` Chang S. Bae
2026-09-15 3:16 ` Sohil Mehta
2026-08-26 3:50 ` [PATCH v4 0/7] KVM: x86: Add LASS virtualization support Kishen Maloor
2026-08-27 3:18 ` Chen, Farrah
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