KVM: arm64: Move userspace system registers into separate function

There's a semantic difference between the EL1 registers that control
operation of a kernel running in EL1 and EL1 registers that only control
userspace execution in EL0.  Since we can defer saving/restoring the
latter, move them into their own function.

The ARMv8 ARM (ARM DDI 0487C.a) Section D10.2.1 recommends that
ACTLR_EL1 has no effect on the processor when running the VHE host, and
we can therefore move this register into the EL1 state which is only
saved/restored on vcpu_put/load for a VHE host.

We also take this chance to rename the function saving/restoring the
remaining system register to make it clear this function deals with
the EL1 system registers.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
index 99fc605..d5a5145 100644 (file)
--- a/arch/arm64/kvm/hyp/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
@@ -28,24 +28,33 @@ static void __hyp_text __sysreg_do_nothing(struct kvm_cpu_context *ctxt) { }
 /*
  * Non-VHE: Both host and guest must save everything.
  *
- * VHE: Host must save tpidr*_el0, actlr_el1, mdscr_el1, sp_el0,
+ * VHE: Host must save tpidr*_el0, mdscr_el1, sp_el0,
  * and guest must save everything.
  */
 
 static void __hyp_text __sysreg_save_common_state(struct kvm_cpu_context *ctxt)
 {
-       ctxt->sys_regs[ACTLR_EL1]       = read_sysreg(actlr_el1);
-       ctxt->sys_regs[TPIDR_EL0]       = read_sysreg(tpidr_el0);
-       ctxt->sys_regs[TPIDRRO_EL0]     = read_sysreg(tpidrro_el0);
        ctxt->sys_regs[MDSCR_EL1]       = read_sysreg(mdscr_el1);
+
+       /*
+        * The host arm64 Linux uses sp_el0 to point to 'current' and it must
+        * therefore be saved/restored on every entry/exit to/from the guest.
+        */
        ctxt->gp_regs.regs.sp           = read_sysreg(sp_el0);
 }
 
-static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
+static void __hyp_text __sysreg_save_user_state(struct kvm_cpu_context *ctxt)
+{
+       ctxt->sys_regs[TPIDR_EL0]       = read_sysreg(tpidr_el0);
+       ctxt->sys_regs[TPIDRRO_EL0]     = read_sysreg(tpidrro_el0);
+}
+
+static void __hyp_text __sysreg_save_el1_state(struct kvm_cpu_context *ctxt)
 {
        ctxt->sys_regs[MPIDR_EL1]       = read_sysreg(vmpidr_el2);
        ctxt->sys_regs[CSSELR_EL1]      = read_sysreg(csselr_el1);
        ctxt->sys_regs[SCTLR_EL1]       = read_sysreg_el1(sctlr);
+       ctxt->sys_regs[ACTLR_EL1]       = read_sysreg(actlr_el1);
        ctxt->sys_regs[CPACR_EL1]       = read_sysreg_el1(cpacr);
        ctxt->sys_regs[TTBR0_EL1]       = read_sysreg_el1(ttbr0);
        ctxt->sys_regs[TTBR1_EL1]       = read_sysreg_el1(ttbr1);
@@ -73,35 +82,46 @@ static void __hyp_text __sysreg_save_state(struct kvm_cpu_context *ctxt)
 }
 
 static hyp_alternate_select(__sysreg_call_save_host_state,
-                           __sysreg_save_state, __sysreg_do_nothing,
+                           __sysreg_save_el1_state, __sysreg_do_nothing,
                            ARM64_HAS_VIRT_HOST_EXTN);
 
 void __hyp_text __sysreg_save_host_state(struct kvm_cpu_context *ctxt)
 {
        __sysreg_call_save_host_state()(ctxt);
        __sysreg_save_common_state(ctxt);
+       __sysreg_save_user_state(ctxt);
 }
 
 void __hyp_text __sysreg_save_guest_state(struct kvm_cpu_context *ctxt)
 {
-       __sysreg_save_state(ctxt);
+       __sysreg_save_el1_state(ctxt);
        __sysreg_save_common_state(ctxt);
+       __sysreg_save_user_state(ctxt);
 }
 
 static void __hyp_text __sysreg_restore_common_state(struct kvm_cpu_context *ctxt)
 {
-       write_sysreg(ctxt->sys_regs[ACTLR_EL1],   actlr_el1);
-       write_sysreg(ctxt->sys_regs[TPIDR_EL0],   tpidr_el0);
-       write_sysreg(ctxt->sys_regs[TPIDRRO_EL0], tpidrro_el0);
        write_sysreg(ctxt->sys_regs[MDSCR_EL1],   mdscr_el1);
+
+       /*
+        * The host arm64 Linux uses sp_el0 to point to 'current' and it must
+        * therefore be saved/restored on every entry/exit to/from the guest.
+        */
        write_sysreg(ctxt->gp_regs.regs.sp,       sp_el0);
 }
 
-static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
+static void __hyp_text __sysreg_restore_user_state(struct kvm_cpu_context *ctxt)
+{
+       write_sysreg(ctxt->sys_regs[TPIDR_EL0],         tpidr_el0);
+       write_sysreg(ctxt->sys_regs[TPIDRRO_EL0],       tpidrro_el0);
+}
+
+static void __hyp_text __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
 {
        write_sysreg(ctxt->sys_regs[MPIDR_EL1],         vmpidr_el2);
        write_sysreg(ctxt->sys_regs[CSSELR_EL1],        csselr_el1);
        write_sysreg_el1(ctxt->sys_regs[SCTLR_EL1],     sctlr);
+       write_sysreg(ctxt->sys_regs[ACTLR_EL1],         actlr_el1);
        write_sysreg_el1(ctxt->sys_regs[CPACR_EL1],     cpacr);
        write_sysreg_el1(ctxt->sys_regs[TTBR0_EL1],     ttbr0);
        write_sysreg_el1(ctxt->sys_regs[TTBR1_EL1],     ttbr1);
@@ -129,19 +149,21 @@ static void __hyp_text __sysreg_restore_state(struct kvm_cpu_context *ctxt)
 }
 
 static hyp_alternate_select(__sysreg_call_restore_host_state,
-                           __sysreg_restore_state, __sysreg_do_nothing,
+                           __sysreg_restore_el1_state, __sysreg_do_nothing,
                            ARM64_HAS_VIRT_HOST_EXTN);
 
 void __hyp_text __sysreg_restore_host_state(struct kvm_cpu_context *ctxt)
 {
        __sysreg_call_restore_host_state()(ctxt);
        __sysreg_restore_common_state(ctxt);
+       __sysreg_restore_user_state(ctxt);
 }
 
 void __hyp_text __sysreg_restore_guest_state(struct kvm_cpu_context *ctxt)
 {
-       __sysreg_restore_state(ctxt);
+       __sysreg_restore_el1_state(ctxt);
        __sysreg_restore_common_state(ctxt);
+       __sysreg_restore_user_state(ctxt);
 }
 
 void __hyp_text __sysreg32_save_state(struct kvm_vcpu *vcpu)