| Message ID | 20201109113233.9012-14-dbrazdil@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Opt-in always-on nVHE hypervisor | expand |
On 2020-11-09 11:32, David Brazdil wrote: > When nVHE hyp starts interception host's PSCI CPU_ON SMCs, it will need > to install KVM on the newly booted CPU before returning to the host. > Add > an entry point which expects the same kvm_nvhe_init_params struct as > the > __kvm_hyp_init HVC in the CPU_ON context argument (x0). > > The entry point initializes EL2 state with the same init_el2_state > macro > used by the kernel's entry point. It then initializes KVM using the > same > helper function used in the __kvm_hyp_init HVC. > > When done, the entry point branches to a function provided in the init > params. > > Signed-off-by: David Brazdil <dbrazdil@google.com> > --- > arch/arm64/include/asm/kvm_asm.h | 1 + > arch/arm64/kernel/asm-offsets.c | 1 + > arch/arm64/kvm/hyp/nvhe/hyp-init.S | 30 ++++++++++++++++++++++++++++++ > 3 files changed, 32 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_asm.h > b/arch/arm64/include/asm/kvm_asm.h > index 893327d1e449..efb4872bb29f 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -155,6 +155,7 @@ struct kvm_nvhe_init_params { > unsigned long tpidr_el2; > unsigned long hyp_stack_ptr; > unsigned long vector_ptr; > + unsigned long psci_cpu_entry_fn; > }; > > /* Translate a kernel address @ptr into its equivalent linear mapping > */ > diff --git a/arch/arm64/kernel/asm-offsets.c > b/arch/arm64/kernel/asm-offsets.c > index 0cbb86135c7c..ffc84e68ad97 100644 > --- a/arch/arm64/kernel/asm-offsets.c > +++ b/arch/arm64/kernel/asm-offsets.c > @@ -114,6 +114,7 @@ int main(void) > DEFINE(NVHE_INIT_TPIDR_EL2, offsetof(struct kvm_nvhe_init_params, > tpidr_el2)); > DEFINE(NVHE_INIT_STACK_PTR, offsetof(struct kvm_nvhe_init_params, > hyp_stack_ptr)); > DEFINE(NVHE_INIT_VECTOR_PTR, offsetof(struct kvm_nvhe_init_params, > vector_ptr)); > + DEFINE(NVHE_INIT_PSCI_CPU_ENTRY_FN, offsetof(struct > kvm_nvhe_init_params, psci_cpu_entry_fn)); > #endif > #ifdef CONFIG_CPU_PM > DEFINE(CPU_CTX_SP, offsetof(struct cpu_suspend_ctx, sp)); > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S > b/arch/arm64/kvm/hyp/nvhe/hyp-init.S > index 1697d25756e9..f999a35b2c8c 100644 > --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S > @@ -6,6 +6,7 @@ > > #include <linux/arm-smccc.h> > #include <linux/linkage.h> > +#include <linux/irqchip/arm-gic-v3.h> This should probably be included from the file that provides init_el2_state. > > #include <asm/alternative.h> > #include <asm/assembler.h> > @@ -159,6 +160,35 @@ alternative_else_nop_endif > ret > SYM_CODE_END(___kvm_hyp_init) > > +SYM_CODE_START(__kvm_hyp_cpu_entry) > + msr SPsel, #1 // We want to use SP_EL{1,2} > + > + /* > + * Check that the core was booted in EL2. Loop indefinitely if not > + * because it cannot be safely given to the host without installing > KVM. > + */ > + mrs x1, CurrentEL > + cmp x1, #CurrentEL_EL2 > + b.ne . This is a bit brutal. Consider using a WFE/WFI loop as we have in other places already (see __secondary_too_slow for example). > + > + /* Initialize EL2 CPU state to sane values. */ > + mov x29, x0 > + init_el2_state nvhe > + mov x0, x29 > + > + /* > + * Load hyp VA of C entry function. Must do so before switching on > the > + * MMU because the struct pointer is PA and not identity-mapped in > hyp. > + */ > + ldr x29, [x0, #NVHE_INIT_PSCI_CPU_ENTRY_FN] > + > + /* Enable MMU, set vectors and stack. */ > + bl ___kvm_hyp_init > + > + /* Leave idmap. */ > + br x29 To a point I made against an earlier patch: psci_cpu_entry_fn seems to be a HYP VA, and really needs to be documented as such, because this is pretty hard to follow otherwise. > +SYM_CODE_END(__kvm_hyp_cpu_entry) > + > SYM_CODE_START(__kvm_handle_stub_hvc) > cmp x0, #HVC_SOFT_RESTART > b.ne 1f Thanks, M.
> > #ifdef CONFIG_CPU_PM > > DEFINE(CPU_CTX_SP, offsetof(struct cpu_suspend_ctx, sp)); > > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S > > b/arch/arm64/kvm/hyp/nvhe/hyp-init.S > > index 1697d25756e9..f999a35b2c8c 100644 > > --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S > > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S > > @@ -6,6 +6,7 @@ > > > > #include <linux/arm-smccc.h> > > #include <linux/linkage.h> > > +#include <linux/irqchip/arm-gic-v3.h> > > This should probably be included from the file that provides init_el2_state. Agreed. This is a workaround for the fact that the arm-gic* headers don't play nice with each other (define the same constants). Including arm-gic-v3.h in kvm_asm.h will trigger macro redefine warnings in vgic*-v2.c because they include arm-gic.h. Another option is to create a header just for el2 init. Would that be preferable? Other ideas? > > > > > #include <asm/alternative.h> > > #include <asm/assembler.h> > > @@ -159,6 +160,35 @@ alternative_else_nop_endif > > ret > > SYM_CODE_END(___kvm_hyp_init) > > > > +SYM_CODE_START(__kvm_hyp_cpu_entry) > > + msr SPsel, #1 // We want to use SP_EL{1,2} > > + > > + /* > > + * Check that the core was booted in EL2. Loop indefinitely if not > > + * because it cannot be safely given to the host without installing > > KVM. > > + */ > > + mrs x1, CurrentEL > > + cmp x1, #CurrentEL_EL2 > > + b.ne . > > This is a bit brutal. Consider using a WFE/WFI loop as we have in other > places already (see __secondary_too_slow for example). Ack > > + > > + /* Initialize EL2 CPU state to sane values. */ > > + mov x29, x0 > > + init_el2_state nvhe > > + mov x0, x29 > > + > > + /* > > + * Load hyp VA of C entry function. Must do so before switching on the > > + * MMU because the struct pointer is PA and not identity-mapped in > > hyp. > > + */ > > + ldr x29, [x0, #NVHE_INIT_PSCI_CPU_ENTRY_FN] > > + > > + /* Enable MMU, set vectors and stack. */ > > + bl ___kvm_hyp_init > > + > > + /* Leave idmap. */ > > + br x29 > > To a point I made against an earlier patch: psci_cpu_entry_fn seems to be a > HYP > VA, and really needs to be documented as such, because this is pretty hard > to > follow otherwise. > > > +SYM_CODE_END(__kvm_hyp_cpu_entry) > > + > > SYM_CODE_START(__kvm_handle_stub_hvc) > > cmp x0, #HVC_SOFT_RESTART > > b.ne 1f > > Thanks, > > M. > -- > Jazz is not dead. It just smells funny...
On 2020-11-16 11:49, David Brazdil wrote: >> > #ifdef CONFIG_CPU_PM >> > DEFINE(CPU_CTX_SP, offsetof(struct cpu_suspend_ctx, sp)); >> > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S >> > b/arch/arm64/kvm/hyp/nvhe/hyp-init.S >> > index 1697d25756e9..f999a35b2c8c 100644 >> > --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S >> > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S >> > @@ -6,6 +6,7 @@ >> > >> > #include <linux/arm-smccc.h> >> > #include <linux/linkage.h> >> > +#include <linux/irqchip/arm-gic-v3.h> >> >> This should probably be included from the file that provides >> init_el2_state. > > Agreed. This is a workaround for the fact that the arm-gic* headers > don't play > nice with each other (define the same constants). Ah, that... > Including arm-gic-v3.h in > kvm_asm.h will trigger macro redefine warnings in vgic*-v2.c because > they > include arm-gic.h. Boo. > Another option is to create a header just for el2 init. Would that be > preferable? Other ideas? Having an asm/el2_setup.h file feels like a better option. After all, it is in no way KVM specific, and having the macros hanging around in asm/kvm_asm.h feels odd. M.
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index 893327d1e449..efb4872bb29f 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -155,6 +155,7 @@ struct kvm_nvhe_init_params { unsigned long tpidr_el2; unsigned long hyp_stack_ptr; unsigned long vector_ptr; + unsigned long psci_cpu_entry_fn; }; /* Translate a kernel address @ptr into its equivalent linear mapping */ diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 0cbb86135c7c..ffc84e68ad97 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -114,6 +114,7 @@ int main(void) DEFINE(NVHE_INIT_TPIDR_EL2, offsetof(struct kvm_nvhe_init_params, tpidr_el2)); DEFINE(NVHE_INIT_STACK_PTR, offsetof(struct kvm_nvhe_init_params, hyp_stack_ptr)); DEFINE(NVHE_INIT_VECTOR_PTR, offsetof(struct kvm_nvhe_init_params, vector_ptr)); + DEFINE(NVHE_INIT_PSCI_CPU_ENTRY_FN, offsetof(struct kvm_nvhe_init_params, psci_cpu_entry_fn)); #endif #ifdef CONFIG_CPU_PM DEFINE(CPU_CTX_SP, offsetof(struct cpu_suspend_ctx, sp)); diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S index 1697d25756e9..f999a35b2c8c 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S @@ -6,6 +6,7 @@ #include <linux/arm-smccc.h> #include <linux/linkage.h> +#include <linux/irqchip/arm-gic-v3.h> #include <asm/alternative.h> #include <asm/assembler.h> @@ -159,6 +160,35 @@ alternative_else_nop_endif ret SYM_CODE_END(___kvm_hyp_init) +SYM_CODE_START(__kvm_hyp_cpu_entry) + msr SPsel, #1 // We want to use SP_EL{1,2} + + /* + * Check that the core was booted in EL2. Loop indefinitely if not + * because it cannot be safely given to the host without installing KVM. + */ + mrs x1, CurrentEL + cmp x1, #CurrentEL_EL2 + b.ne . + + /* Initialize EL2 CPU state to sane values. */ + mov x29, x0 + init_el2_state nvhe + mov x0, x29 + + /* + * Load hyp VA of C entry function. Must do so before switching on the + * MMU because the struct pointer is PA and not identity-mapped in hyp. + */ + ldr x29, [x0, #NVHE_INIT_PSCI_CPU_ENTRY_FN] + + /* Enable MMU, set vectors and stack. */ + bl ___kvm_hyp_init + + /* Leave idmap. */ + br x29 +SYM_CODE_END(__kvm_hyp_cpu_entry) + SYM_CODE_START(__kvm_handle_stub_hvc) cmp x0, #HVC_SOFT_RESTART b.ne 1f
When nVHE hyp starts interception host's PSCI CPU_ON SMCs, it will need to install KVM on the newly booted CPU before returning to the host. Add an entry point which expects the same kvm_nvhe_init_params struct as the __kvm_hyp_init HVC in the CPU_ON context argument (x0). The entry point initializes EL2 state with the same init_el2_state macro used by the kernel's entry point. It then initializes KVM using the same helper function used in the __kvm_hyp_init HVC. When done, the entry point branches to a function provided in the init params. Signed-off-by: David Brazdil <dbrazdil@google.com> --- arch/arm64/include/asm/kvm_asm.h | 1 + arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kvm/hyp/nvhe/hyp-init.S | 30 ++++++++++++++++++++++++++++++ 3 files changed, 32 insertions(+)