From: Yu Zhang <yu.c.zhang@linux.intel.com>
To: Binbin Wu <binbin.wu@linux.intel.com>
Cc: Robert Hoo <robert.hu@linux.intel.com>,
seanjc@google.com, pbonzini@redhat.com, yuan.yao@linux.intel.com,
jingqi.liu@intel.com, weijiang.yang@intel.com,
chao.gao@intel.com, isaku.yamahata@intel.com,
kirill.shutemov@linux.intel.com, kvm@vger.kernel.org
Subject: Re: [PATCH v4 9/9] KVM: x86: LAM: Expose LAM CPUID to user space VMM
Date: Tue, 21 Feb 2023 19:13:28 +0800 [thread overview]
Message-ID: <20230221111328.jaosfrcw2da7jx76@linux.intel.com> (raw)
In-Reply-To: <fc84dd84-67c5-5565-b989-7e6bb9116c6e@linux.intel.com>
>
> The special handling for LA57 is from the patch "kvm: x86: Return LA57
> feature based on hardware capability".
> https://lore.kernel.org/lkml/1548950983-18458-1-git-send-email-yu.c.zhang@linux.intel.com/
>
> The reason is host kernel may disable 5-level paging using cmdline parameter
> 'no5lvl', and it will clear the feature bit for LA57 in boot_cpu_data.
> boot_cpu_data is queried in kvm_set_cpu_caps to derive kvm cpu cap masks.
>
> " VMs can still benefit from extended linear address width, e.g. to enhance
> features like ASLR" even when host doesn't use 5-level paging.
> So, the patch sets LA57 based on hardware capability.
>
> I was just wondering whether LAM could be the similar case that the host
> disabled the feature somehow (e.g via clearcpuid), and the guest still want
> to use it.
Paging modes in root & non-root are orthogonal, so should LAM.
B.R.
Yu
next prev parent reply other threads:[~2023-02-21 11:13 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-09 2:40 [PATCH v4 0/9] Linear Address Masking (LAM) KVM Enabling Robert Hoo
2023-02-09 2:40 ` [PATCH v4 1/9] KVM: x86: Intercept CR4.LAM_SUP when LAM feature is enabled in guest Robert Hoo
2023-02-09 9:21 ` Chao Gao
2023-02-09 12:48 ` Robert Hoo
2023-02-10 3:29 ` Yang, Weijiang
2023-02-10 5:02 ` Robert Hoo
2023-02-10 16:30 ` Sean Christopherson
2023-02-14 1:27 ` Binbin Wu
2023-02-14 6:11 ` Robert Hoo
2023-02-14 9:00 ` Binbin Wu
2023-02-14 12:24 ` Robert Hoo
2023-02-14 12:36 ` Robert Hoo
2023-02-16 5:31 ` Binbin Wu
2023-02-16 5:54 ` Robert Hoo
2023-02-09 2:40 ` [PATCH v4 2/9] KVM: x86: MMU: Clear CR3 LAM bits when allocate shadow root Robert Hoo
2023-02-09 9:55 ` Chao Gao
2023-02-09 13:02 ` Robert Hoo
2023-02-14 2:55 ` Binbin Wu
2023-02-15 1:17 ` Robert Hoo
2023-02-16 2:14 ` Robert Hoo
2023-02-10 3:38 ` Yang, Weijiang
2023-02-11 3:12 ` Robert Hoo
2023-02-09 2:40 ` [PATCH v4 3/9] KVM: x86: MMU: Commets update Robert Hoo
2023-02-10 6:59 ` Chao Gao
2023-02-10 7:55 ` Robert Hoo
2023-02-10 16:54 ` Sean Christopherson
2023-02-09 2:40 ` [PATCH v4 4/9] KVM: x86: MMU: Integrate LAM bits when build guest CR3 Robert Hoo
2023-02-10 14:04 ` Chao Gao
2023-02-11 6:24 ` Robert Hoo
2023-02-11 6:29 ` Robert Hoo
2023-02-09 2:40 ` [PATCH v4 5/9] KVM: x86: Untag LAM bits when applicable Robert Hoo
2023-02-10 15:04 ` Chao Gao
2023-02-11 5:57 ` Robert Hoo
2023-02-16 6:37 ` Binbin Wu
2023-02-09 2:40 ` [PATCH v4 6/9] KVM: x86: When KVM judges CR3 valid or not, consider LAM bits Robert Hoo
2023-02-13 2:01 ` Chao Gao
2023-02-13 13:25 ` Robert Hoo
2023-02-14 6:18 ` Chao Gao
2023-02-14 7:00 ` Chao Gao
2023-02-18 5:44 ` Robert Hoo
2023-02-09 2:40 ` [PATCH v4 7/9] KVM: x86: When guest set CR3, handle LAM bits semantics Robert Hoo
2023-02-13 3:31 ` Chao Gao
2023-02-14 5:28 ` Robert Hoo
2023-02-14 6:48 ` Chao Gao
2023-02-09 2:40 ` [PATCH v4 8/9] KVM: x86: emulation: Apply LAM when emulating data access Robert Hoo
2023-02-13 3:53 ` Chao Gao
2023-02-14 5:38 ` Robert Hoo
2023-02-09 2:40 ` [PATCH v4 9/9] KVM: x86: LAM: Expose LAM CPUID to user space VMM Robert Hoo
2023-02-21 5:47 ` Binbin Wu
2023-02-21 7:26 ` Robert Hoo
2023-02-21 8:26 ` Binbin Wu
2023-02-21 11:13 ` Yu Zhang [this message]
2023-02-21 13:18 ` Binbin Wu
2023-02-21 14:36 ` Robert Hoo
2023-02-09 6:15 ` [PATCH v4 0/9] Linear Address Masking (LAM) KVM Enabling Chao Gao
2023-02-09 12:25 ` Robert Hoo
2023-02-09 17:27 ` Sean Christopherson
2023-02-10 2:07 ` Robert Hoo
2023-02-10 3:17 ` Chao Gao
2023-02-10 8:41 ` Robert Hoo
2023-02-10 8:39 ` Robert Hoo
2023-02-10 9:22 ` Chao Gao
2023-02-13 9:02 ` Binbin Wu
2023-02-13 13:16 ` Robert Hoo
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