Re: [PATCH v4 0/4] Relax canonical checks on some arch msrs

[Sean Christopherson]

On Fri, 06 Sep 2024 18:18:20 -0400, Maxim Levitsky wrote:
> Recently we came up upon a failure where likely the guest writes
> 0xff4547ceb1600000 to MSR_KERNEL_GS_BASE and later on, qemu
> sets this value via KVM_PUT_MSRS, and is rejected by the
> kernel, likely due to not being canonical in 4 level paging.
> 
> One of the way to trigger this is to make the guest enter SMM,
> which causes paging to be disabled, which SMM bios re-enables
> but not the whole 5 level. MSR_KERNEL_GS_BASE on the other
> hand continues to contain old value.
> 
> [...]

Applied to kvm-x86 misc, with some massaging (see responsed to individual
patches).  Thanks!

[1/4] KVM: x86: drop x86.h include from cpuid.h
      https://github.com/kvm-x86/linux/commit/391bd0c520c1
[2/4] KVM: x86: implement emul_is_noncanonical_address using is_noncanonical_address
      https://github.com/kvm-x86/linux/commit/6c45d62536d0
[3/4] KVM: x86: model canonical checks more precisely
      https://github.com/kvm-x86/linux/commit/1b1336d1d858
[4/4] KVM: nVMX: fix canonical check of vmcs12 HOST_RIP
      https://github.com/kvm-x86/linux/commit/14a95598b6e7

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https://github.com/kvm-x86/linux/tree/next