Hi Takahiro,
On 08/05/15 02:18, AKASHI Takahiro wrote:
Cpu must be put back into its initial state, at least, in the following cases in order to shutdown the system and/or re-initialize cpus later on:
- kexec/kdump
- cpu hotplug (offline)
- removing kvm as a module
To address those issues in later patches, this patch adds a tear-down function, kvm_cpu_reset(), that disables D-cache & MMU and restore a vector table to the initial stub at EL2.
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org
arch/arm/kvm/arm.c | 15 +++++++++++++++ arch/arm/kvm/mmu.c | 5 +++++ arch/arm64/include/asm/kvm_asm.h | 1 + arch/arm64/include/asm/kvm_host.h | 11 +++++++++++ arch/arm64/include/asm/kvm_mmu.h | 7 +++++++ arch/arm64/include/asm/virt.h | 11 +++++++++++ arch/arm64/kvm/hyp-init.S | 32 ++++++++++++++++++++++++++++++++ arch/arm64/kvm/hyp.S | 16 +++++++++++++--- 8 files changed, 95 insertions(+), 3 deletions(-)
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 07e7eb1..251ab9e 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -897,6 +897,21 @@ static void cpu_init_hyp_mode(void *dummy) __cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr); } +static void kvm_cpu_reset(void *dummy)
It looks like you can entirely loose the "dummy" parameter. The only reason some function have this is when they are used from an IPI call.
+{
- phys_addr_t boot_pgd_ptr;
- phys_addr_t phys_idmap_start;
- if (__hyp_get_vectors() == hyp_default_vectors)
return;- boot_pgd_ptr = kvm_mmu_get_boot_httbr();
- phys_idmap_start = kvm_get_idmap_start();
- __cpu_reset_hyp_mode(boot_pgd_ptr, phys_idmap_start,
hyp_default_vectors,kvm_virt_to_trampoline(__kvm_hyp_reset));+}
static int hyp_init_cpu_notify(struct notifier_block *self, unsigned long action, void *cpu) { diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c index 3e6859b..3631a37 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1490,6 +1490,11 @@ phys_addr_t kvm_get_idmap_vector(void) return hyp_idmap_vector; } +phys_addr_t kvm_get_idmap_start(void) +{
- return hyp_idmap_start;
+}
int kvm_mmu_init(void) { int err; diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index 4f7310f..f1c16e2 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -118,6 +118,7 @@ struct kvm_vcpu; extern char __kvm_hyp_init[]; extern char __kvm_hyp_init_end[]; +extern char __kvm_hyp_reset[]; extern char __kvm_hyp_vector[]; diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 8ac3c70..6a8da9c 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -199,6 +199,8 @@ struct kvm_vcpu *kvm_arm_get_running_vcpu(void); struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void); u64 kvm_call_hyp(void *hypfn, ...); +void kvm_call_reset(phys_addr_t boot_pgd_ptr, phys_addr_t phys_idmap_start,
unsigned long stub_vector_ptr, unsigned long reset_func);void force_vm_exit(const cpumask_t *mask); void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); @@ -223,6 +225,15 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr, hyp_stack_ptr, vector_ptr); } +static inline void __cpu_reset_hyp_mode(phys_addr_t boot_pgd_ptr,
phys_addr_t phys_idmap_start,unsigned long stub_vector_ptr,unsigned long reset_func)+{
- kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr,
reset_func);+}
struct vgic_sr_vectors { void *save_vgic; void *restore_vgic; diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 6458b53..facfd6d 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -96,6 +96,7 @@ void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu); phys_addr_t kvm_mmu_get_httbr(void); phys_addr_t kvm_mmu_get_boot_httbr(void); phys_addr_t kvm_get_idmap_vector(void); +phys_addr_t kvm_get_idmap_start(void); int kvm_mmu_init(void); void kvm_clear_hyp_idmap(void); @@ -305,5 +306,11 @@ static inline void __kvm_flush_dcache_pud(pud_t pud) void kvm_set_way_flush(struct kvm_vcpu *vcpu); void kvm_toggle_cache(struct kvm_vcpu *vcpu, bool was_enabled); +extern char __hyp_idmap_text_start[];
If you're defining it here, then it worth considering removing the similar declaration from mmu.c.
+#define kvm_virt_to_trampoline(x) \
(TRAMPOLINE_VA \+ ((unsigned long)(x) \- ((unsigned long)__hyp_idmap_text_start & PAGE_MASK)))#endif /* __ASSEMBLY__ */ #endif /* __ARM64_KVM_MMU_H__ */ diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index 3070096..7fcd087 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -61,6 +61,17 @@ #define BOOT_CPU_MODE_EL1 (0xe11) #define BOOT_CPU_MODE_EL2 (0xe12) +/*
- HVC_RESET - Reset cpu in EL2 to initial state.
- @x0: entry address in trampoline code in va
- @x1: identical mapping page table in pa
- @x2: start address of identical mapping in pa
- @x3: initial stub vector in pa
- */
+#define HVC_RESET 5
#ifndef __ASSEMBLY__ /* diff --git a/arch/arm64/kvm/hyp-init.S b/arch/arm64/kvm/hyp-init.S index c319116..2614cfc 100644 --- a/arch/arm64/kvm/hyp-init.S +++ b/arch/arm64/kvm/hyp-init.S @@ -115,6 +115,38 @@ target: /* We're now in the trampoline code, switch page tables */ eret ENDPROC(__kvm_hyp_init)
- /*
* x0: HYP boot pgd* x1: HYP phys_idmap_start* x2: HYP stub vectors*/+ENTRY(__kvm_hyp_reset)
- /* We're in trampoline code in VA, switch back to boot page tables */
- msr ttbr0_el2, x0
- isb
- /* Invalidate the old TLBs */
- tlbi alle2
- dsb sy
- /* 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
- ldr x1, =SCTLR_EL2_FLAGS
- bic x0, x0, x1 // Clear SCTL_M and etc
- msr sctlr_el2, x0
- isb
- /* Install stub vectors */
- msr vbar_el2, x2
Instead of using a parameter, can't you just do
adr x2, __hyp_stub_vectors msr vbar_el2, x2
? I can't imagine a case where we don't want this behaviour, and this would slightly simplify the calling convention.
- eret
+ENDPROC(__kvm_hyp_reset)
- .ltorg
.popsection diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S index fd085ec..7c3bdee 100644 --- a/arch/arm64/kvm/hyp.S +++ b/arch/arm64/kvm/hyp.S @@ -1136,6 +1136,11 @@ ENTRY(kvm_call_hyp) ret ENDPROC(kvm_call_hyp) +ENTRY(kvm_call_reset)
- hvc #HVC_RESET
- ret
+ENDPROC(kvm_call_reset)
.macro invalid_vector label, target .align 2 \label: @@ -1179,10 +1184,14 @@ el1_sync: // Guest trapped into EL2 cmp x18, #HVC_GET_VECTORS b.ne 1f mrs x0, vbar_el2
- b 2f
- b 3f
How about renaming this to something like "do_eret" once and for all so that we stop this dance each time someone adds a new entry point?
-1: /* Default to HVC_CALL_HYP. */
- /* jump into trampoline code */
+1: cmp x18, #HVC_RESET
- b.ne 2f
- br x3 // no return
Same here. If we're always jumping to the trampoline code, why do we have to pass it as a parameter?
+2: /* Default to HVC_CALL_HYP. */ push lr, xzr /* @@ -1196,7 +1205,8 @@ el1_sync: // Guest trapped into EL2 blr lr pop lr, xzr -2: eret
+3: eret el1_trap: /*
Thanks,
M.