Re: [PATCH v2 0/4] KVM: nSVM: avoid TOC/TOU race when checking vmcb12

From: Paolo Bonzini
Date: Tue Sep 28 2021 - 12:52:57 EST

On 17/09/21 14:03, Emanuele Giuseppe Esposito wrote:
Currently there is a TOC/TOU race between the check of vmcb12's
efer, cr0 and cr4 registers and the later save of their values in
svm_set_*, because the guest could modify the values in the meanwhile.

To solve this issue, this serie introuces and uses svm->
structure in enter_svm_guest_mode to save the current value of efer,
cr0 and cr4 and later use these to set the vcpu->arch.* state.

Patch 1 just refactor the code to simplify the next two patches,
patch 2 introduces svm-> to cache the efer, cr0 and cr4 fields
and in patch 3 and 4 we use it to avoid TOC/TOU races.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@xxxxxxxxxx>

Most of my remarks from the RFC still apply, so I will wait for v3. Thanks, and sorry for the time between send and review.