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KVM: arm64: Move userspace system registers into separate function
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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 <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Signed-off-by: Christoffer Dall <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
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@chazy
chazy authored and Marc Zyngier committed Mar 19, 2018
1 parent 04fef05 commit 060701f
Showing 1 changed file with 35 additions and 13 deletions.
48 changes: 35 additions & 13 deletions arch/arm64/kvm/hyp/sysreg-sr.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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)
Expand Down

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