From f359182291c757cdf77bcd014c025d1ed6b87662 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 8 Feb 2021 09:57:13 +0000 Subject: arm64: Provide an 'upgrade to VHE' stub hypercall As we are about to change the way a VHE system boots, let's provide the core helper, in the form of a stub hypercall that enables VHE and replicates the full EL1 context at EL2, thanks to EL1 and VHE-EL2 being extremely similar. On exception return, the kernel carries on at EL2. Fancy! Nothing calls this new hypercall yet, so no functional change. Signed-off-by: Marc Zyngier Acked-by: David Brazdil Acked-by: Catalin Marinas Link: https://lore.kernel.org/r/20210208095732.3267263-5-maz@kernel.org Signed-off-by: Will Deacon --- arch/arm64/kernel/hyp-stub.S | 76 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 74 insertions(+), 2 deletions(-) (limited to 'arch/arm64/kernel/hyp-stub.S') diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S index 160f5881a0b7..3f3dbbe8914d 100644 --- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S @@ -8,9 +8,9 @@ #include #include -#include #include +#include #include #include #include @@ -47,10 +47,13 @@ SYM_CODE_END(__hyp_stub_vectors) SYM_CODE_START_LOCAL(el1_sync) cmp x0, #HVC_SET_VECTORS - b.ne 2f + b.ne 1f msr vbar_el2, x1 b 9f +1: cmp x0, #HVC_VHE_RESTART + b.eq mutate_to_vhe + 2: cmp x0, #HVC_SOFT_RESTART b.ne 3f mov x0, x2 @@ -70,6 +73,75 @@ SYM_CODE_START_LOCAL(el1_sync) eret SYM_CODE_END(el1_sync) +// nVHE? No way! Give me the real thing! +SYM_CODE_START_LOCAL(mutate_to_vhe) + // Be prepared to fail + mov_q x0, HVC_STUB_ERR + + // Sanity check: MMU *must* be off + mrs x1, sctlr_el2 + tbnz x1, #0, 1f + + // Needs to be VHE capable, obviously + mrs x1, id_aa64mmfr1_el1 + ubfx x1, x1, #ID_AA64MMFR1_VHE_SHIFT, #4 + cbz x1, 1f + + // Engage the VHE magic! + mov_q x0, HCR_HOST_VHE_FLAGS + msr hcr_el2, x0 + isb + + // Doesn't do much on VHE, but still, worth a shot + init_el2_state vhe + + // Use the EL1 allocated stack, per-cpu offset + mrs x0, sp_el1 + mov sp, x0 + mrs x0, tpidr_el1 + msr tpidr_el2, x0 + + // FP configuration, vectors + mrs_s x0, SYS_CPACR_EL12 + msr cpacr_el1, x0 + mrs_s x0, SYS_VBAR_EL12 + msr vbar_el1, x0 + + // Transfer the MM state from EL1 to EL2 + mrs_s x0, SYS_TCR_EL12 + msr tcr_el1, x0 + mrs_s x0, SYS_TTBR0_EL12 + msr ttbr0_el1, x0 + mrs_s x0, SYS_TTBR1_EL12 + msr ttbr1_el1, x0 + mrs_s x0, SYS_MAIR_EL12 + msr mair_el1, x0 + isb + + // Invalidate TLBs before enabling the MMU + tlbi vmalle1 + dsb nsh + + // Enable the EL2 S1 MMU, as set up from EL1 + mrs_s x0, SYS_SCTLR_EL12 + set_sctlr_el1 x0 + + // Disable the EL1 S1 MMU for a good measure + mov_q x0, INIT_SCTLR_EL1_MMU_OFF + msr_s SYS_SCTLR_EL12, x0 + + // Hack the exception return to stay at EL2 + mrs x0, spsr_el1 + and x0, x0, #~PSR_MODE_MASK + mov x1, #PSR_MODE_EL2h + orr x0, x0, x1 + msr spsr_el1, x0 + + mov x0, xzr + +1: eret +SYM_CODE_END(mutate_to_vhe) + .macro invalid_vector label SYM_CODE_START_LOCAL(\label) b \label -- cgit