KVM: x86/mmu: Precisely invalidate MMU root_role during CPUID update
Set kvm_mmu_page_role.invalid to mark the various MMU root_roles invalid during CPUID update in order to force a refresh, instead of zeroing out the entire role. This fixes a bug where kvm_mmu_free_roots() incorrectly thinks a root is indirect, i.e. not a TDP MMU, due to "direct" being zeroed, which in turn causes KVM to take mmu_lock for write instead of read. Note, paving over the entire role was largely unintentional, commit7a458f0e1b
("KVM: x86/mmu: remove extended bits from mmu_role, rename field") simply missed that "invalid" could be set. Fixes:576a15de8d
("KVM: x86/mmu: Free TDP MMU roots while holding mmy_lock for read") Reported-by: syzbot+dc308fcfcd53f987de73@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/0000000000009b38080614c49bdb@google.com Cc: Phi Nguyen <phind.uet@gmail.com> Link: https://lore.kernel.org/r/20240408231115.1387279-1-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
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@ -5576,9 +5576,9 @@ void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu)
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* that problem is swept under the rug; KVM's CPUID API is horrific and
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* it's all but impossible to solve it without introducing a new API.
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*/
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vcpu->arch.root_mmu.root_role.word = 0;
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vcpu->arch.guest_mmu.root_role.word = 0;
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vcpu->arch.nested_mmu.root_role.word = 0;
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vcpu->arch.root_mmu.root_role.invalid = 1;
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vcpu->arch.guest_mmu.root_role.invalid = 1;
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vcpu->arch.nested_mmu.root_role.invalid = 1;
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vcpu->arch.root_mmu.cpu_role.ext.valid = 0;
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vcpu->arch.guest_mmu.cpu_role.ext.valid = 0;
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vcpu->arch.nested_mmu.cpu_role.ext.valid = 0;
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