On Fri, Jan 28, 2022 at 12:18:21PM +0000, Marc Zyngier wrote: > KVM internally uses accessor functions when reading or writing the > guest's system registers. This takes care of accessing either the stored > copy or using the "live" EL1 system registers when the host uses VHE. > > With the introduction of virtual EL2 we add a bunch of EL2 system > registers, which now must also be taken care of: > - If the guest is running in vEL2, and we access an EL1 sysreg, we must > revert to the stored version of that, and not use the CPU's copy. > - If the guest is running in vEL1, and we access an EL2 sysreg, we must > also use the stored version, since the CPU carries the EL1 copy. > - Some EL2 system registers are supposed to affect the current execution > of the system, so we need to put them into their respective EL1 > counterparts. For this we need to define a mapping between the two. > This is done using the newly introduced struct el2_sysreg_map. > - Some EL2 system registers have a different format than their EL1 > counterpart, so we need to translate them before writing them to the > CPU. This is done using an (optional) translate function in the map. > - There are the three special registers SP_EL2, SPSR_EL2 and ELR_EL2, > which need some separate handling (SPSR_EL2 is being handled in a > separate patch). > > All of these cases are now wrapped into the existing accessor functions, > so KVM users wouldn't need to care whether they access EL2 or EL1 > registers and also which state the guest is in. > > This handles what was formerly known as the "shadow state" dynamically, > without requiring a separate copy for each vCPU EL. > > Reviewed-by: Ganapatrao Kulkarni <gankulkarni@xxxxxxxxxxxxxxxxxxxxxx> > Reviewed-by: Alexandru Elisei <alexandru.elisei@xxxxxxx> > Co-developed-by: Andre Przywara <andre.przywara@xxxxxxx> > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> Reviewed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx> -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
