forked from Minki/linux
f7ed45be3b
Provides complete world-switch implementation to switch to other guests running in non-secure modes. Includes Hyp exception handlers that capture necessary exception information and stores the information on the VCPU and KVM structures. The following Hyp-ABI is also documented in the code: Hyp-ABI: Calling HYP-mode functions from host (in SVC mode): Switching to Hyp mode is done through a simple HVC #0 instruction. The exception vector code will check that the HVC comes from VMID==0 and if so will push the necessary state (SPSR, lr_usr) on the Hyp stack. - r0 contains a pointer to a HYP function - r1, r2, and r3 contain arguments to the above function. - The HYP function will be called with its arguments in r0, r1 and r2. On HYP function return, we return directly to SVC. A call to a function executing in Hyp mode is performed like the following: <svc code> ldr r0, =BSYM(my_hyp_fn) ldr r1, =my_param hvc #0 ; Call my_hyp_fn(my_param) from HYP mode <svc code> Otherwise, the world-switch is pretty straight-forward. All state that can be modified by the guest is first backed up on the Hyp stack and the VCPU values is loaded onto the hardware. State, which is not loaded, but theoretically modifiable by the guest is protected through the virtualiation features to generate a trap and cause software emulation. Upon guest returns, all state is restored from hardware onto the VCPU struct and the original state is restored from the Hyp-stack onto the hardware. SMP support using the VMPIDR calculated on the basis of the host MPIDR and overriding the low bits with KVM vcpu_id contributed by Marc Zyngier. Reuse of VMIDs has been implemented by Antonios Motakis and adapated from a separate patch into the appropriate patches introducing the functionality. Note that the VMIDs are stored per VM as required by the ARM architecture reference manual. To support VFP/NEON we trap those instructions using the HPCTR. When we trap, we switch the FPU. After a guest exit, the VFP state is returned to the host. When disabling access to floating point instructions, we also mask FPEXC_EN in order to avoid the guest receiving Undefined instruction exceptions before we have a chance to switch back the floating point state. We are reusing vfp_hard_struct, so we depend on VFPv3 being enabled in the host kernel, if not, we still trap cp10 and cp11 in order to inject an undefined instruction exception whenever the guest tries to use VFP/NEON. VFP/NEON developed by Antionios Motakis and Rusty Russell. Aborts that are permission faults, and not stage-1 page table walk, do not report the faulting address in the HPFAR. We have to resolve the IPA, and store it just like the HPFAR register on the VCPU struct. If the IPA cannot be resolved, it means another CPU is playing with the page tables, and we simply restart the guest. This quirk was fixed by Marc Zyngier. Reviewed-by: Will Deacon <will.deacon@arm.com> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com> |
||
|---|---|---|
| .. | ||
| alpha | ||
| arm | ||
| arm64 | ||
| avr32 | ||
| blackfin | ||
| c6x | ||
| cris | ||
| frv | ||
| h8300 | ||
| hexagon | ||
| ia64 | ||
| m32r | ||
| m68k | ||
| microblaze | ||
| mips | ||
| mn10300 | ||
| openrisc | ||
| parisc | ||
| powerpc | ||
| s390 | ||
| score | ||
| sh | ||
| sparc | ||
| tile | ||
| um | ||
| unicore32 | ||
| x86 | ||
| xtensa | ||
| .gitignore | ||
| Kconfig | ||