Messages in this thread | | | Date | Wed, 11 Nov 2020 11:57:55 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH v1 13/24] kvm: arm64: Add CPU entry point in nVHE hyp |
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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. -- Jazz is not dead. It just smells funny...
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