From 3421e9d88d7ae70fbc8c903e44a5acace8ae2d29 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 30 Jun 2016 18:40:44 +0100 Subject: [PATCH] arm64: KVM: Simplify HYP init/teardown Now that we only have the "merged page tables" case to deal with, there is a bunch of things we can simplify in the HYP code (both at init and teardown time). Signed-off-by: Marc Zyngier Signed-off-by: Christoffer Dall --- arch/arm64/include/asm/kvm_host.h | 12 ++---- arch/arm64/kvm/hyp-init.S | 61 ++++--------------------------- arch/arm64/kvm/hyp/entry.S | 19 ---------- arch/arm64/kvm/hyp/hyp-entry.S | 15 ++++++++ arch/arm64/kvm/reset.c | 11 ------ 5 files changed, 26 insertions(+), 92 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 49095fc4b482..88462c307510 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -48,7 +48,6 @@ int __attribute_const__ kvm_target_cpu(void); int kvm_reset_vcpu(struct kvm_vcpu *vcpu); int kvm_arch_dev_ioctl_check_extension(long ext); -unsigned long kvm_hyp_reset_entry(void); void __extended_idmap_trampoline(phys_addr_t boot_pgd, phys_addr_t idmap_start); struct kvm_arch { @@ -357,19 +356,14 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr, * Call initialization code, and switch to the full blown * HYP code. */ - __kvm_call_hyp((void *)boot_pgd_ptr, pgd_ptr, - hyp_stack_ptr, vector_ptr); + __kvm_call_hyp((void *)pgd_ptr, hyp_stack_ptr, vector_ptr); } +void __kvm_hyp_teardown(void); static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr, phys_addr_t phys_idmap_start) { - /* - * Call reset code, and switch back to stub hyp vectors. - * Uses __kvm_call_hyp() to avoid kaslr's kvm_ksym_ref() translation. - */ - __kvm_call_hyp((void *)kvm_hyp_reset_entry(), - boot_pgd_ptr, phys_idmap_start); + kvm_call_hyp(__kvm_hyp_teardown, phys_idmap_start); } static inline void kvm_arch_hardware_unsetup(void) {} diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S index a873a6d8be90..6b29d3d9e1f2 100644 --- a/arch/arm64/kvm/hyp-init.S +++ b/arch/arm64/kvm/hyp-init.S @@ -53,10 +53,9 @@ __invalid: b . /* - * x0: HYP boot pgd - * x1: HYP pgd - * x2: HYP stack - * x3: HYP vectors + * x0: HYP pgd + * x1: HYP stack + * x2: HYP vectors */ __do_hyp_init: @@ -110,71 +109,27 @@ __do_hyp_init: msr sctlr_el2, x4 isb - /* Skip the trampoline dance if we merged the boot and runtime PGDs */ - cmp x0, x1 - b.eq merged - - /* MMU is now enabled. Get ready for the trampoline dance */ - ldr x4, =TRAMPOLINE_VA - adr x5, target - bfi x4, x5, #0, #PAGE_SHIFT - br x4 - -target: /* We're now in the trampoline code, switch page tables */ - msr ttbr0_el2, x1 - isb - - /* Invalidate the old TLBs */ - tlbi alle2 - dsb sy - -merged: /* Set the stack and new vectors */ + kern_hyp_va x1 + mov sp, x1 kern_hyp_va x2 - mov sp, x2 - kern_hyp_va x3 - msr vbar_el2, x3 + msr vbar_el2, x2 /* Hello, World! */ eret ENDPROC(__kvm_hyp_init) /* - * Reset kvm back to the hyp stub. This is the trampoline dance in - * reverse. If kvm used an extended idmap, __extended_idmap_trampoline - * calls this code directly in the idmap. In this case switching to the - * boot tables is a no-op. - * - * x0: HYP boot pgd - * x1: HYP phys_idmap_start + * Reset kvm back to the hyp stub. */ ENTRY(__kvm_hyp_reset) - /* We're in trampoline code in VA, switch back to boot page tables */ - msr ttbr0_el2, x0 - isb - - /* Ensure the PA branch doesn't find a stale tlb entry or stale code. */ - ic iallu - tlbi alle2 - dsb sy - isb - - /* Branch into PA space */ - adr x0, 1f - bfi x1, x0, #0, #PAGE_SHIFT - br x1 - /* We're now in idmap, disable MMU */ -1: mrs x0, sctlr_el2 + mrs x0, sctlr_el2 ldr x1, =SCTLR_ELx_FLAGS bic x0, x0, x1 // Clear SCTL_M and etc msr sctlr_el2, x0 isb - /* Invalidate the old TLBs */ - tlbi alle2 - dsb sy - /* Install stub vectors */ adr_l x0, __hyp_stub_vectors msr vbar_el2, x0 diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S index 70254a65bd5b..ce9e5e5f28cf 100644 --- a/arch/arm64/kvm/hyp/entry.S +++ b/arch/arm64/kvm/hyp/entry.S @@ -164,22 +164,3 @@ alternative_endif eret ENDPROC(__fpsimd_guest_restore) - -/* - * When using the extended idmap, we don't have a trampoline page we can use - * while we switch pages tables during __kvm_hyp_reset. Accessing the idmap - * directly would be ideal, but if we're using the extended idmap then the - * idmap is located above HYP_PAGE_OFFSET, and the address will be masked by - * kvm_call_hyp using kern_hyp_va. - * - * x0: HYP boot pgd - * x1: HYP phys_idmap_start - */ -ENTRY(__extended_idmap_trampoline) - mov x4, x1 - adr_l x3, __kvm_hyp_reset - - /* insert __kvm_hyp_reset()s offset into phys_idmap_start */ - bfi x4, x3, #0, #PAGE_SHIFT - br x4 -ENDPROC(__extended_idmap_trampoline) diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index 2d87f36d5cb4..f6d9694ae3b1 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -62,6 +62,21 @@ ENTRY(__vhe_hyp_call) isb ret ENDPROC(__vhe_hyp_call) + +/* + * Compute the idmap address of __kvm_hyp_reset based on the idmap + * start passed as a parameter, and jump there. + * + * x0: HYP phys_idmap_start + */ +ENTRY(__kvm_hyp_teardown) + mov x4, x0 + adr_l x3, __kvm_hyp_reset + + /* insert __kvm_hyp_reset()s offset into phys_idmap_start */ + bfi x4, x3, #0, #PAGE_SHIFT + br x4 +ENDPROC(__kvm_hyp_teardown) el1_sync: // Guest trapped into EL2 save_x0_to_x3 diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 8ed7e4a92e95..79f324823340 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -132,14 +132,3 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) /* Reset timer */ return kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq); } - -unsigned long kvm_hyp_reset_entry(void) -{ - /* - * KVM is running with merged page tables, which don't have the - * trampoline page mapped. We know the idmap is still mapped, - * but can't be called into directly. Use - * __extended_idmap_trampoline to do the call. - */ - return (unsigned long)kvm_ksym_ref(__extended_idmap_trampoline); -}