On Mon, Mar 04, 2019 at 06:07:14PM +0800, Yang Weijiang wrote: > On Mon, Mar 04, 2019 at 10:53:27AM -0800, Sean Christopherson wrote: > > On Mon, Feb 25, 2019 at 09:27:13PM +0800, Yang Weijiang wrote: > > > The CET runtime settings, i.e., CET state control bits(IA32_U_CET/ > > > IA32_S_CET), CET SSP(IA32_PL3_SSP/IA32_PL0_SSP) and SSP table address > > > (IA32_INTERRUPT_SSP_TABLE_ADDR) are task/thread specific, therefore, > > > OS needs to save/restore the states properly during context switch, > > > e.g., task/thread switching, interrupt/exception handling, it uses > > > xsaves/xrstors to achieve that. > > > > > > The difference between VMCS CET area fields and xsave CET area, is that > > > the former is for state retention during Guest/Host context > > > switch while the latter is for state retention during OS execution. > > > > > > Linux currently doesn't support CPL1 and CPL2, so SSPs for these level > > > are skipped here. > > > > But don't we want to allow a guest to access the MSRs regardless of > > the host kernel's behavior? > > > Do you see any necessity of exposing the access to guest? No, but isn't exposing them to the guest effectively free since XSAVES and XRSTORS will always save/restore them along with SSP0 and SSP3?
