> On Aug 20, 2020, at 08:21, Tom Lendacky <[email protected]> wrote: > On 8/20/20 10:10 AM, Sean Christopherson wrote: >> >> Pretty sure current->thread.gsbase can be stale, i.e. this needs: >> current_save_fsgs(); > > I did try adding current_save_fsgs() in svm_vcpu_load(), saving the > current->thread.gsbase value to a new variable in the svm struct. I then used > that variable in the wrmsrl below, but it still crashed.
Then, current->thread.gsbase is from __rdgsbase_inactive() which is user GSBASE. If you do the wrmsrl below, it overwrites the current GSBASE with the user value. >> wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gsbase); Thanks, Chang
