mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-13 15:19:26 -04:00
4736d85f0d
Commitee3a5f9e3d("KVM: x86: Do runtime CPUID update before updating vcpu->arch.cpuid_entries") moved tweaking of the supplied CPUID data earlier in kvm_set_cpuid() but __kvm_update_cpuid_runtime() actually uses 'vcpu->arch.kvm_cpuid' (though __kvm_find_kvm_cpuid_features()) which gets set later in kvm_set_cpuid(). In some cases, e.g. when kvm_set_cpuid() is called for the first time and 'vcpu->arch.kvm_cpuid' is clear, __kvm_find_kvm_cpuid_features() fails to find KVM PV feature entry and the logic which clears KVM_FEATURE_PV_UNHALT after enabling KVM_X86_DISABLE_EXITS_HLT does not work. The logic, introduced by the commitee3a5f9e3d("KVM: x86: Do runtime CPUID update before updating vcpu->arch.cpuid_entries") must stay: the supplied CPUID data is tweaked by KVM first (__kvm_update_cpuid_runtime()) and checked later (kvm_check_cpuid()) and the actual data (vcpu->arch.cpuid_*, vcpu->arch.kvm_cpuid, vcpu->arch.xen.cpuid,..) is only updated on success. Switch to searching for KVM_SIGNATURE in the supplied CPUID data to discover KVM PV feature entry instead of using stale 'vcpu->arch.kvm_cpuid'. While on it, drop pointless "&& (best->eax & (1 << KVM_FEATURE_PV_UNHALT)" check when clearing KVM_FEATURE_PV_UNHALT bit. Fixes:ee3a5f9e3d("KVM: x86: Do runtime CPUID update before updating vcpu->arch.cpuid_entries") Reported-and-tested-by: Li RongQing <lirongqing@baidu.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Link: https://lore.kernel.org/r/20240228101837.93642-3-vkuznets@redhat.com Signed-off-by: Sean Christopherson <seanjc@google.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.