| Message ID | 1427111639-4575-2-git-send-email-takahiro.akashi@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Takahiro, On Mon, 2015-03-23 at 20:53 +0900, AKASHI Takahiro wrote: > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > index 3e6859b..428f41c 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c ... > +phys_addr_t kvm_get_stub_vectors(void) > +{ > + return virt_to_phys(__hyp_stub_vectors); > +} The stub vectors are not part of KVM, but part of kernel, so to me a routine get_hyp_stub_vectors() with a prototype in asm/virt.h, then a definition in maybe kernel/process.c, or a new file kernel/virt.c makes more sense. > +unsigned long kvm_reset_func_entry(void) > +{ > + /* VA of __kvm_hyp_reset in trampline code */ > + return TRAMPOLINE_VA + (__kvm_hyp_reset - __hyp_idmap_text_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..97ee2fc 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -116,8 +116,11 @@ > struct kvm; > struct kvm_vcpu; > > +extern char __hyp_stub_vectors[]; I think this should at least be in asm/virt.h, or better, have a get_hyp_stub_vectors(). > 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..97f88fe 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -199,6 +199,7 @@ 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(unsigned long reset_func, ...); kvm_call_reset() takes a fixed number of args, so we shouldn't have it as a variadic here. I think a variadic routine complicates things for my kvm_call_reset() suggestion below. > void force_vm_exit(const cpumask_t *mask); > void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); > > @@ -223,6 +224,15 @@ 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(unsigned long reset_func, > + phys_addr_t boot_pgd_ptr, > + phys_addr_t phys_idmap_start, > + unsigned long stub_vector_ptr) > + kvm_call_reset(reset_func, boot_pgd_ptr, > + phys_idmap_start, stub_vector_ptr); Why not switch the order of the args here to: kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr, reset_func) This will eliminate the register shifting in the HVC_RESET hcall vector which becomes just 'br x3'. > diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S > index fd085ec..aee75f9 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 +1184,10 @@ el1_sync: // Guest trapped into EL2 > cmp x18, #HVC_GET_VECTORS > b.ne 1f > mrs x0, vbar_el2 > - b 2f > - > -1: /* Default to HVC_CALL_HYP. */ It seems you are deleting this comment and also removing the logic that makes HVC_CALL_HYP the default. > + b 3f > > +1: cmp x18, #HVC_CALL_HYP > + b.ne 2f > push lr, xzr > > /* > @@ -1196,7 +1201,23 @@ el1_sync: // Guest trapped into EL2 > blr lr > > pop lr, xzr > -2: eret > + b 3f > + > + /* > + * shuffle the parameters and jump into trampline code. > + */ > +2: cmp x18, #HVC_RESET > + b.ne 3f > + > + mov x18, x0 > + mov x0, x1 > + mov x1, x2 > + mov x2, x3 > + mov x3, x4 > + br x18 > + /* not reach here */ > + > +3: eret We don't need to change labels for each new hcall, I think just this is OK: cmp x18, #HVC_GET_VECTORS b.ne 1f mrs x0, vbar_el2 b 2f +1: cmp x18, #HVC_RESET + b.ne 1f + br x3 // No return 1: /* Default to HVC_CALL_HYP. */ ... -Geoff
Geoff, On 03/24/2015 01:46 AM, Geoff Levand wrote: > Hi Takahiro, > > On Mon, 2015-03-23 at 20:53 +0900, AKASHI Takahiro wrote: >> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c >> index 3e6859b..428f41c 100644 >> --- a/arch/arm/kvm/mmu.c >> +++ b/arch/arm/kvm/mmu.c > ... >> +phys_addr_t kvm_get_stub_vectors(void) >> +{ >> + return virt_to_phys(__hyp_stub_vectors); >> +} > > The stub vectors are not part of KVM, but part of kernel, > so to me a routine get_hyp_stub_vectors() with a prototype > in asm/virt.h, then a definition in maybe > kernel/process.c, or a new file kernel/virt.c makes more > sense. Right. Will rename the function to get_hyp_stub_vectors() and put it in asm/virt.h. >> +unsigned long kvm_reset_func_entry(void) >> +{ >> + /* VA of __kvm_hyp_reset in trampline code */ >> + return TRAMPOLINE_VA + (__kvm_hyp_reset - __hyp_idmap_text_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..97ee2fc 100644 >> --- a/arch/arm64/include/asm/kvm_asm.h >> +++ b/arch/arm64/include/asm/kvm_asm.h >> @@ -116,8 +116,11 @@ >> struct kvm; >> struct kvm_vcpu; >> >> +extern char __hyp_stub_vectors[]; > > I think this should at least be in asm/virt.h, or better, > have a get_hyp_stub_vectors(). See above. >> 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..97f88fe 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -199,6 +199,7 @@ 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(unsigned long reset_func, ...); > > kvm_call_reset() takes a fixed number of args, so we shouldn't > have it as a variadic here. I think a variadic routine > complicates things for my kvm_call_reset() suggestion below. > >> void force_vm_exit(const cpumask_t *mask); >> void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); >> >> @@ -223,6 +224,15 @@ 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(unsigned long reset_func, >> + phys_addr_t boot_pgd_ptr, >> + phys_addr_t phys_idmap_start, >> + unsigned long stub_vector_ptr) > >> + kvm_call_reset(reset_func, boot_pgd_ptr, >> + phys_idmap_start, stub_vector_ptr); > > Why not switch the order of the args here to: > > kvm_call_reset(boot_pgd_ptr, phys_idmap_start, stub_vector_ptr, reset_func) > > This will eliminate the register shifting in the HVC_RESET > hcall vector which becomes just 'br x3'. Looks nice. FYI, initially I wanted to implement kvm_cpu_reset() using kvm_call_hyp() and so both have similar code. > >> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S >> index fd085ec..aee75f9 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 +1184,10 @@ el1_sync: // Guest trapped into EL2 >> cmp x18, #HVC_GET_VECTORS >> b.ne 1f >> mrs x0, vbar_el2 >> - b 2f >> - >> -1: /* Default to HVC_CALL_HYP. */ > > It seems you are deleting this comment and also > removing the logic that makes HVC_CALL_HYP the default. Yeah, I didn't think of that. But IIUC, we don't have to handle it as default case because all interfaces come from kvm_call_hyp() once KVM is initialized. >> + b 3f >> >> +1: cmp x18, #HVC_CALL_HYP >> + b.ne 2f >> push lr, xzr >> >> /* >> @@ -1196,7 +1201,23 @@ el1_sync: // Guest trapped into EL2 >> blr lr >> >> pop lr, xzr >> -2: eret >> + b 3f >> + >> + /* >> + * shuffle the parameters and jump into trampline code. >> + */ >> +2: cmp x18, #HVC_RESET >> + b.ne 3f >> + >> + mov x18, x0 >> + mov x0, x1 >> + mov x1, x2 >> + mov x2, x3 >> + mov x3, x4 >> + br x18 >> + /* not reach here */ >> + >> +3: eret > > We don't need to change labels for each new hcall, I > think just this is OK: > > cmp x18, #HVC_GET_VECTORS > b.ne 1f > mrs x0, vbar_el2 > b 2f > > +1: cmp x18, #HVC_RESET > + b.ne 1f > + br x3 // No return > > 1: /* Default to HVC_CALL_HYP. */ > ... Will fix it. Thanks, -Takahiro AKASHI > -Geoff > > >
Hi Takahiro, On 23/03/15 11:53, 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: > 1) kexec/kdump > 2) cpu hotplug (offline) > 3) 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. Thanks for having a look at this. > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> > --- > arch/arm/kvm/arm.c | 18 ++++++++++++++++ > arch/arm/kvm/mmu.c | 16 +++++++++++++++ > arch/arm64/include/asm/kvm_asm.h | 3 +++ > arch/arm64/include/asm/kvm_host.h | 10 +++++++++ > arch/arm64/include/asm/kvm_mmu.h | 3 +++ > arch/arm64/include/asm/virt.h | 11 ++++++++++ > arch/arm64/kvm/hyp-init.S | 41 +++++++++++++++++++++++++++++++++++++ > arch/arm64/kvm/hyp.S | 29 ++++++++++++++++++++++---- > 8 files changed, 127 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 5560f74..35c8bc0 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -897,6 +897,24 @@ static void cpu_init_hyp_mode(void *dummy) > __cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr); > } > > +void kvm_cpu_reset(void *dummy) Given that the notifier introduced in patch #2 lives in the same file, this could be made static, couldn't it? > +{ > + phys_addr_t boot_pgd_ptr; > + phys_addr_t phys_idmap_start; > + unsigned long reset_func; > + unsigned long vector_ptr; > + > + if (__hyp_get_vectors() == hyp_default_vectors) > + return; > + > + reset_func = kvm_reset_func_entry(); > + boot_pgd_ptr = kvm_mmu_get_boot_httbr(); > + phys_idmap_start = kvm_get_idmap_start(); > + vector_ptr = kvm_get_stub_vectors(); Isn't that hyp_default_vectors already? > + __cpu_reset_hyp_mode(reset_func, > + boot_pgd_ptr, phys_idmap_start, vector_ptr); > +} > + > 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..428f41c 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c > @@ -1490,6 +1490,22 @@ phys_addr_t kvm_get_idmap_vector(void) > return hyp_idmap_vector; > } > > +phys_addr_t kvm_get_idmap_start(void) > +{ > + return hyp_idmap_start; > +} > + > +phys_addr_t kvm_get_stub_vectors(void) > +{ > + return virt_to_phys(__hyp_stub_vectors); > +} As Geoff already mentioned, this doesn't belong in KVM. But I don't think you need it, as explained above. > + > +unsigned long kvm_reset_func_entry(void) > +{ > + /* VA of __kvm_hyp_reset in trampline code */ > + return TRAMPOLINE_VA + (__kvm_hyp_reset - __hyp_idmap_text_start); > +} If you need to compute addresses in the trampoline page, it would be better to have a generic macro that takes a kernel VA, and turns it into a trampoline VA. > + > 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..97ee2fc 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -116,8 +116,11 @@ > struct kvm; > struct kvm_vcpu; > > +extern char __hyp_stub_vectors[]; Not a KVM thing (for the same reason). > + > 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..97f88fe 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -199,6 +199,7 @@ 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(unsigned long reset_func, ...); You seem to have a single call signature for this function, and have defined all the parameters below. You can drop the variadic aspect. > void force_vm_exit(const cpumask_t *mask); > void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); > > @@ -223,6 +224,15 @@ 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(unsigned long reset_func, > + phys_addr_t boot_pgd_ptr, > + phys_addr_t phys_idmap_start, > + unsigned long stub_vector_ptr) > +{ > + kvm_call_reset(reset_func, boot_pgd_ptr, > + phys_idmap_start, stub_vector_ptr); > +} > + > 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..36be582 100644 > --- a/arch/arm64/include/asm/kvm_mmu.h > +++ b/arch/arm64/include/asm/kvm_mmu.h > @@ -96,6 +96,9 @@ 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); > +phys_addr_t kvm_get_stub_vectors(void); > +unsigned long kvm_reset_func_entry(void); > int kvm_mmu_init(void); > void kvm_clear_hyp_idmap(void); > > 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..ca7e6bf 100644 > --- a/arch/arm64/kvm/hyp-init.S > +++ b/arch/arm64/kvm/hyp-init.S > @@ -115,6 +115,47 @@ 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 */ > + /* Invalidate the old TLBs */ > + tlbi alle2 > + dsb sy Invalidating the TLBs before switching TTBR0_EL2 is unlikely to have the effect you want. > + /* Switch back to boot page tables */ > + msr ttbr0_el2, x0 > + isb This is the place where you want TLBI to occur. > + /* Branch into PA space */ > + adr x0, 1f > + bfi x1, x0, #0, #PAGE_SHIFT > + br x1 > + > + /* We're now in idmap */ > +1: /* Invalidate the old TLBs again */ > + tlbi alle2 > + dsb sy See? This is the only TLBI that actually makes sense. Now, given that you are actually disabling the MMU, I'm not sure these TBLIs make much sense. > + /* Disable MMU */ > + mrs x0, sctlr_el2 > + and x1, x0, #SCTLR_EL2_EE > + orr x0, x0, x1 // preserve endianness of EL2 > + ldr x1, =SCTLR_EL2_FLAGS > + eor x1, x1, xzr > + bic x0, x0, x1 // Clear SCTL_M and etc > + msr sctlr_el2, x0 > + isb > + > + /* Switch back to stub vectors */ > + msr vbar_el2, x2 > + > + eret > +ENDPROC(__kvm_hyp_reset) > + > .ltorg > > .popsection > diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S > index fd085ec..aee75f9 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 +1184,10 @@ el1_sync: // Guest trapped into EL2 > cmp x18, #HVC_GET_VECTORS > b.ne 1f > mrs x0, vbar_el2 > - b 2f > - > -1: /* Default to HVC_CALL_HYP. */ > + b 3f > > +1: cmp x18, #HVC_CALL_HYP > + b.ne 2f > push lr, xzr > > /* > @@ -1196,7 +1201,23 @@ el1_sync: // Guest trapped into EL2 > blr lr > > pop lr, xzr > -2: eret > + b 3f > + > + /* > + * shuffle the parameters and jump into trampline code. > + */ > +2: cmp x18, #HVC_RESET > + b.ne 3f > + > + mov x18, x0 > + mov x0, x1 > + mov x1, x2 > + mov x2, x3 > + mov x3, x4 > + br x18 I'd rather move the shuffling of the registers before the HVC call. > + /* not reach here */ > + > +3: eret > > el1_trap: > /* > Thanks, M.
Marc, On 03/24/2015 07:00 PM, Marc Zyngier wrote: > Hi Takahiro, > > On 23/03/15 11:53, 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: >> 1) kexec/kdump >> 2) cpu hotplug (offline) >> 3) 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. > > Thanks for having a look at this. > >> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> >> --- >> arch/arm/kvm/arm.c | 18 ++++++++++++++++ >> arch/arm/kvm/mmu.c | 16 +++++++++++++++ >> arch/arm64/include/asm/kvm_asm.h | 3 +++ >> arch/arm64/include/asm/kvm_host.h | 10 +++++++++ >> arch/arm64/include/asm/kvm_mmu.h | 3 +++ >> arch/arm64/include/asm/virt.h | 11 ++++++++++ >> arch/arm64/kvm/hyp-init.S | 41 +++++++++++++++++++++++++++++++++++++ >> arch/arm64/kvm/hyp.S | 29 ++++++++++++++++++++++---- >> 8 files changed, 127 insertions(+), 4 deletions(-) >> >> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c >> index 5560f74..35c8bc0 100644 >> --- a/arch/arm/kvm/arm.c >> +++ b/arch/arm/kvm/arm.c >> @@ -897,6 +897,24 @@ static void cpu_init_hyp_mode(void *dummy) >> __cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr); >> } >> >> +void kvm_cpu_reset(void *dummy) > > Given that the notifier introduced in patch #2 lives in the same file, > this could be made static, couldn't it? Yes. Will fix it. >> +{ >> + phys_addr_t boot_pgd_ptr; >> + phys_addr_t phys_idmap_start; >> + unsigned long reset_func; >> + unsigned long vector_ptr; >> + >> + if (__hyp_get_vectors() == hyp_default_vectors) >> + return; >> + >> + reset_func = kvm_reset_func_entry(); >> + boot_pgd_ptr = kvm_mmu_get_boot_httbr(); >> + phys_idmap_start = kvm_get_idmap_start(); >> + vector_ptr = kvm_get_stub_vectors(); > > Isn't that hyp_default_vectors already? Yeah, I already use it in kvm_cpu_reset(). Will fix it. >> + __cpu_reset_hyp_mode(reset_func, >> + boot_pgd_ptr, phys_idmap_start, vector_ptr); >> +} >> + >> 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..428f41c 100644 >> --- a/arch/arm/kvm/mmu.c >> +++ b/arch/arm/kvm/mmu.c >> @@ -1490,6 +1490,22 @@ phys_addr_t kvm_get_idmap_vector(void) >> return hyp_idmap_vector; >> } >> >> +phys_addr_t kvm_get_idmap_start(void) >> +{ >> + return hyp_idmap_start; >> +} >> + >> +phys_addr_t kvm_get_stub_vectors(void) >> +{ >> + return virt_to_phys(__hyp_stub_vectors); >> +} > > As Geoff already mentioned, this doesn't belong in KVM. But I don't > think you need it, as explained above. Will remove it. >> + >> +unsigned long kvm_reset_func_entry(void) >> +{ >> + /* VA of __kvm_hyp_reset in trampline code */ >> + return TRAMPOLINE_VA + (__kvm_hyp_reset - __hyp_idmap_text_start); >> +} > > If you need to compute addresses in the trampoline page, it would be > better to have a generic macro that takes a kernel VA, and turns it into > a trampoline VA. This is the only place to calculate the address. But will fix it. >> + >> 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..97ee2fc 100644 >> --- a/arch/arm64/include/asm/kvm_asm.h >> +++ b/arch/arm64/include/asm/kvm_asm.h >> @@ -116,8 +116,11 @@ >> struct kvm; >> struct kvm_vcpu; >> >> +extern char __hyp_stub_vectors[]; > > Not a KVM thing (for the same reason). Will remove it. >> + >> 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..97f88fe 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -199,6 +199,7 @@ 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(unsigned long reset_func, ...); > > You seem to have a single call signature for this function, and have > defined all the parameters below. You can drop the variadic aspect. As Geoff suggested, the arguments of __cpu_reset_hyp_mode() and kvm_call_reset() will be shuffled as in this order: 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 +224,15 @@ 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(unsigned long reset_func, >> + phys_addr_t boot_pgd_ptr, >> + phys_addr_t phys_idmap_start, >> + unsigned long stub_vector_ptr) >> +{ >> + kvm_call_reset(reset_func, boot_pgd_ptr, >> + phys_idmap_start, stub_vector_ptr); >> +} >> + >> 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..36be582 100644 >> --- a/arch/arm64/include/asm/kvm_mmu.h >> +++ b/arch/arm64/include/asm/kvm_mmu.h >> @@ -96,6 +96,9 @@ 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); >> +phys_addr_t kvm_get_stub_vectors(void); >> +unsigned long kvm_reset_func_entry(void); >> int kvm_mmu_init(void); >> void kvm_clear_hyp_idmap(void); >> >> 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..ca7e6bf 100644 >> --- a/arch/arm64/kvm/hyp-init.S >> +++ b/arch/arm64/kvm/hyp-init.S >> @@ -115,6 +115,47 @@ 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 */ >> + /* Invalidate the old TLBs */ >> + tlbi alle2 >> + dsb sy > > Invalidating the TLBs before switching TTBR0_EL2 is unlikely to have the > effect you want. > >> + /* Switch back to boot page tables */ >> + msr ttbr0_el2, x0 >> + isb > > This is the place where you want TLBI to occur. Will remove tlbi above and put it here. >> + /* Branch into PA space */ >> + adr x0, 1f >> + bfi x1, x0, #0, #PAGE_SHIFT >> + br x1 >> + >> + /* We're now in idmap */ >> +1: /* Invalidate the old TLBs again */ >> + tlbi alle2 >> + dsb sy > > See? This is the only TLBI that actually makes sense. Now, given that > you are actually disabling the MMU, I'm not sure these TBLIs make much > sense. Probably you're right, but otherwise, I guess, bogus TLB might remain and be used when MMU get enabled again. (MMU setting would be the same across disabling/enabling hyp mode though.) >> + /* Disable MMU */ >> + mrs x0, sctlr_el2 >> + and x1, x0, #SCTLR_EL2_EE >> + orr x0, x0, x1 // preserve endianness of EL2 >> + ldr x1, =SCTLR_EL2_FLAGS >> + eor x1, x1, xzr >> + bic x0, x0, x1 // Clear SCTL_M and etc >> + msr sctlr_el2, x0 >> + isb >> + >> + /* Switch back to stub vectors */ >> + msr vbar_el2, x2 >> + >> + eret >> +ENDPROC(__kvm_hyp_reset) >> + >> .ltorg >> >> .popsection >> diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S >> index fd085ec..aee75f9 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 +1184,10 @@ el1_sync: // Guest trapped into EL2 >> cmp x18, #HVC_GET_VECTORS >> b.ne 1f >> mrs x0, vbar_el2 >> - b 2f >> - >> -1: /* Default to HVC_CALL_HYP. */ >> + b 3f >> >> +1: cmp x18, #HVC_CALL_HYP >> + b.ne 2f >> push lr, xzr >> >> /* >> @@ -1196,7 +1201,23 @@ el1_sync: // Guest trapped into EL2 >> blr lr >> >> pop lr, xzr >> -2: eret >> + b 3f >> + >> + /* >> + * shuffle the parameters and jump into trampline code. >> + */ >> +2: cmp x18, #HVC_RESET >> + b.ne 3f >> + >> + mov x18, x0 >> + mov x0, x1 >> + mov x1, x2 >> + mov x2, x3 >> + mov x3, x4 >> + br x18 > > I'd rather move the shuffling of the registers before the HVC call. See above. Thanks, -Takahiro AKASHI >> + /* not reach here */ >> + >> +3: eret >> >> el1_trap: >> /* >> > > Thanks, > > M. >
Hi Takahiro, On 25/03/15 08:06, AKASHI Takahiro wrote: >>> + /* Switch back to boot page tables */ >>> + msr ttbr0_el2, x0 >>> + isb >> >> This is the place where you want TLBI to occur. > > Will remove tlbi above and put it here. There is only need for one TLBI, if at all. >>> + /* Branch into PA space */ >>> + adr x0, 1f >>> + bfi x1, x0, #0, #PAGE_SHIFT >>> + br x1 >>> + >>> + /* We're now in idmap */ >>> +1: /* Invalidate the old TLBs again */ >>> + tlbi alle2 >>> + dsb sy >> >> See? This is the only TLBI that actually makes sense. Now, given that >> you are actually disabling the MMU, I'm not sure these TBLIs make much >> sense. > > Probably you're right, but > otherwise, I guess, bogus TLB might remain and be used when MMU get enabled again. > (MMU setting would be the same across disabling/enabling hyp mode though.) Anyone enabling the MMU must invalidate the TLB before doing so (we've been caught by that before). Invalidation on the way out doesn't hurt, but it also give a false sense of security. I'll leave it up to you. Thanks, M.
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 5560f74..35c8bc0 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -897,6 +897,24 @@ static void cpu_init_hyp_mode(void *dummy) __cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr); } +void kvm_cpu_reset(void *dummy) +{ + phys_addr_t boot_pgd_ptr; + phys_addr_t phys_idmap_start; + unsigned long reset_func; + unsigned long vector_ptr; + + if (__hyp_get_vectors() == hyp_default_vectors) + return; + + reset_func = kvm_reset_func_entry(); + boot_pgd_ptr = kvm_mmu_get_boot_httbr(); + phys_idmap_start = kvm_get_idmap_start(); + vector_ptr = kvm_get_stub_vectors(); + __cpu_reset_hyp_mode(reset_func, + boot_pgd_ptr, phys_idmap_start, vector_ptr); +} + 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..428f41c 100644 --- a/arch/arm/kvm/mmu.c +++ b/arch/arm/kvm/mmu.c @@ -1490,6 +1490,22 @@ phys_addr_t kvm_get_idmap_vector(void) return hyp_idmap_vector; } +phys_addr_t kvm_get_idmap_start(void) +{ + return hyp_idmap_start; +} + +phys_addr_t kvm_get_stub_vectors(void) +{ + return virt_to_phys(__hyp_stub_vectors); +} + +unsigned long kvm_reset_func_entry(void) +{ + /* VA of __kvm_hyp_reset in trampline code */ + return TRAMPOLINE_VA + (__kvm_hyp_reset - __hyp_idmap_text_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..97ee2fc 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -116,8 +116,11 @@ struct kvm; struct kvm_vcpu; +extern char __hyp_stub_vectors[]; + 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..97f88fe 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -199,6 +199,7 @@ 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(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 +224,15 @@ 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(unsigned long reset_func, + phys_addr_t boot_pgd_ptr, + phys_addr_t phys_idmap_start, + unsigned long stub_vector_ptr) +{ + kvm_call_reset(reset_func, boot_pgd_ptr, + phys_idmap_start, stub_vector_ptr); +} + 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..36be582 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -96,6 +96,9 @@ 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); +phys_addr_t kvm_get_stub_vectors(void); +unsigned long kvm_reset_func_entry(void); int kvm_mmu_init(void); void kvm_clear_hyp_idmap(void); 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..ca7e6bf 100644 --- a/arch/arm64/kvm/hyp-init.S +++ b/arch/arm64/kvm/hyp-init.S @@ -115,6 +115,47 @@ 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 */ + /* Invalidate the old TLBs */ + tlbi alle2 + dsb sy + + /* Switch back to boot page tables */ + msr ttbr0_el2, x0 + isb + + /* Branch into PA space */ + adr x0, 1f + bfi x1, x0, #0, #PAGE_SHIFT + br x1 + + /* We're now in idmap */ +1: /* Invalidate the old TLBs again */ + tlbi alle2 + dsb sy + + /* Disable MMU */ + mrs x0, sctlr_el2 + and x1, x0, #SCTLR_EL2_EE + orr x0, x0, x1 // preserve endianness of EL2 + ldr x1, =SCTLR_EL2_FLAGS + eor x1, x1, xzr + bic x0, x0, x1 // Clear SCTL_M and etc + msr sctlr_el2, x0 + isb + + /* Switch back to stub vectors */ + msr vbar_el2, x2 + + eret +ENDPROC(__kvm_hyp_reset) + .ltorg .popsection diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S index fd085ec..aee75f9 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 +1184,10 @@ el1_sync: // Guest trapped into EL2 cmp x18, #HVC_GET_VECTORS b.ne 1f mrs x0, vbar_el2 - b 2f - -1: /* Default to HVC_CALL_HYP. */ + b 3f +1: cmp x18, #HVC_CALL_HYP + b.ne 2f push lr, xzr /* @@ -1196,7 +1201,23 @@ el1_sync: // Guest trapped into EL2 blr lr pop lr, xzr -2: eret + b 3f + + /* + * shuffle the parameters and jump into trampline code. + */ +2: cmp x18, #HVC_RESET + b.ne 3f + + mov x18, x0 + mov x0, x1 + mov x1, x2 + mov x2, x3 + mov x3, x4 + br x18 + /* not reach here */ + +3: eret el1_trap: /*
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: 1) kexec/kdump 2) cpu hotplug (offline) 3) 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 | 18 ++++++++++++++++ arch/arm/kvm/mmu.c | 16 +++++++++++++++ arch/arm64/include/asm/kvm_asm.h | 3 +++ arch/arm64/include/asm/kvm_host.h | 10 +++++++++ arch/arm64/include/asm/kvm_mmu.h | 3 +++ arch/arm64/include/asm/virt.h | 11 ++++++++++ arch/arm64/kvm/hyp-init.S | 41 +++++++++++++++++++++++++++++++++++++ arch/arm64/kvm/hyp.S | 29 ++++++++++++++++++++++---- 8 files changed, 127 insertions(+), 4 deletions(-)