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    SubjectRe: [PATCH v1 08/24] kvm: arm64: Move hyp-init params to a per-CPU struct
    On 2020-11-09 11:32, David Brazdil wrote:
    > Once we start initializing KVM on newly booted cores before the rest of
    > the kernel, parameters to __do_hyp_init will need to be provided by EL2
    > rather than EL1. At that point it will not be possible to pass its four
    > arguments directly because PSCI_CPU_ON only supports one context
    > argument.
    >
    > Refactor __do_hyp_init to accept its parameters in a struct. This
    > prepares the code for KVM booting cores as well as removes any limits
    > on
    > the number of __do_hyp_init arguments.
    >
    > Signed-off-by: David Brazdil <dbrazdil@google.com>
    > ---
    > arch/arm64/include/asm/kvm_asm.h | 7 +++++++
    > arch/arm64/include/asm/kvm_hyp.h | 4 ++++
    > arch/arm64/kernel/asm-offsets.c | 4 ++++
    > arch/arm64/kvm/arm.c | 26 ++++++++++++++------------
    > arch/arm64/kvm/hyp/nvhe/hyp-init.S | 21 ++++++++++-----------
    > arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 ++
    > 6 files changed, 41 insertions(+), 23 deletions(-)
    >
    > diff --git a/arch/arm64/include/asm/kvm_asm.h
    > b/arch/arm64/include/asm/kvm_asm.h
    > index 54387ccd1ab2..a49a87a186c3 100644
    > --- a/arch/arm64/include/asm/kvm_asm.h
    > +++ b/arch/arm64/include/asm/kvm_asm.h
    > @@ -150,6 +150,13 @@ extern void *__vhe_undefined_symbol;
    >
    > #endif
    >
    > +struct kvm_nvhe_init_params {
    > + phys_addr_t pgd_ptr;
    > + unsigned long tpidr_el2;
    > + unsigned long hyp_stack_ptr;
    > + unsigned long vector_ptr;
    > +};

    Please add some documentation here, specially indicating what address
    space
    the values are relative to.

    > +
    > /* Translate a kernel address @ptr into its equivalent linear mapping
    > */
    > #define kvm_ksym_ref(ptr) \
    > ({ \
    > diff --git a/arch/arm64/include/asm/kvm_hyp.h
    > b/arch/arm64/include/asm/kvm_hyp.h
    > index 6b664de5ec1f..a3289071f3d8 100644
    > --- a/arch/arm64/include/asm/kvm_hyp.h
    > +++ b/arch/arm64/include/asm/kvm_hyp.h
    > @@ -15,6 +15,10 @@
    > DECLARE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
    > DECLARE_PER_CPU(unsigned long, kvm_hyp_vector);
    >
    > +#ifdef __KVM_NVHE_HYPERVISOR__
    > +DECLARE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
    > +#endif
    > +
    > #define read_sysreg_elx(r,nvh,vh) \
    > ({ \
    > u64 reg; \
    > diff --git a/arch/arm64/kernel/asm-offsets.c
    > b/arch/arm64/kernel/asm-offsets.c
    > index 7d32fc959b1a..0cbb86135c7c 100644
    > --- a/arch/arm64/kernel/asm-offsets.c
    > +++ b/arch/arm64/kernel/asm-offsets.c
    > @@ -110,6 +110,10 @@ int main(void)
    > DEFINE(CPU_APGAKEYLO_EL1, offsetof(struct kvm_cpu_context,
    > sys_regs[APGAKEYLO_EL1]));
    > DEFINE(HOST_CONTEXT_VCPU, offsetof(struct kvm_cpu_context,
    > __hyp_running_vcpu));
    > DEFINE(HOST_DATA_CONTEXT, offsetof(struct kvm_host_data,
    > host_ctxt));
    > + DEFINE(NVHE_INIT_PGD_PTR, offsetof(struct kvm_nvhe_init_params,
    > pgd_ptr));
    > + 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));
    > #endif
    > #ifdef CONFIG_CPU_PM
    > DEFINE(CPU_CTX_SP, offsetof(struct cpu_suspend_ctx, sp));
    > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
    > index b85b4294b72d..1a57b6025937 100644
    > --- a/arch/arm64/kvm/arm.c
    > +++ b/arch/arm64/kvm/arm.c
    > @@ -50,6 +50,7 @@ DECLARE_KVM_HYP_PER_CPU(unsigned long,
    > kvm_hyp_vector);
    >
    > static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
    > unsigned long kvm_arm_hyp_percpu_base[NR_CPUS];
    > +DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_init_params,
    > kvm_init_params);
    >
    > /* The VMID used in the VTTBR */
    > static atomic64_t kvm_vmid_gen = ATOMIC64_INIT(1);
    > @@ -1331,10 +1332,7 @@ static int kvm_map_vectors(void)
    >
    > static void cpu_init_hyp_mode(void)
    > {
    > - phys_addr_t pgd_ptr;
    > - unsigned long hyp_stack_ptr;
    > - unsigned long vector_ptr;
    > - unsigned long tpidr_el2;
    > + struct kvm_nvhe_init_params *params =
    > this_cpu_ptr_nvhe_sym(kvm_init_params);
    > struct arm_smccc_res res;
    >
    > /* Switch from the HYP stub to our own HYP init vector */
    > @@ -1345,13 +1343,18 @@ static void cpu_init_hyp_mode(void)
    > * kernel's mapping to the linear mapping, and store it in tpidr_el2
    > * so that we can use adr_l to access per-cpu variables in EL2.
    > */
    > - tpidr_el2 = (unsigned long)this_cpu_ptr_nvhe_sym(__per_cpu_start) -
    > - (unsigned long)kvm_ksym_ref(CHOOSE_NVHE_SYM(__per_cpu_start));
    > + params->tpidr_el2 = (unsigned
    > long)this_cpu_ptr_nvhe_sym(__per_cpu_start) -
    > + (unsigned long)kvm_ksym_ref(CHOOSE_NVHE_SYM(__per_cpu_start));
    >
    > - pgd_ptr = kvm_mmu_get_httbr();
    > - hyp_stack_ptr = __this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE;
    > - hyp_stack_ptr = kern_hyp_va(hyp_stack_ptr);
    > - vector_ptr = (unsigned
    > long)kern_hyp_va(kvm_ksym_ref(__kvm_hyp_host_vector));
    > + params->pgd_ptr = kvm_mmu_get_httbr();
    > + params->vector_ptr = (unsigned
    > long)kern_hyp_va(kvm_ksym_ref(__kvm_hyp_host_vector));
    > + params->hyp_stack_ptr =
    > kern_hyp_va(__this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE);
    > +
    > + /*
    > + * Flush the init params from the data cache because the struct will
    > + * be read from while the MMU is off.

    s/from while/while/ ?

    > + */
    > + __flush_dcache_area(params, sizeof(*params));
    >
    > /*
    > * Call initialization code, and switch to the full blown HYP code.
    > @@ -1360,8 +1363,7 @@ static void cpu_init_hyp_mode(void)
    > * cpus_have_const_cap() wrapper.
    > */
    > BUG_ON(!system_capabilities_finalized());
    > - arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(__kvm_hyp_init),
    > - pgd_ptr, tpidr_el2, hyp_stack_ptr, vector_ptr, &res);
    > + arm_smccc_1_1_hvc(KVM_HOST_SMCCC_FUNC(__kvm_hyp_init),
    > virt_to_phys(params), &res);
    > WARN_ON(res.a0 != SMCCC_RET_SUCCESS);
    >
    > /*
    > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
    > b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
    > index 96e70f976ff5..6f3ac5d428ec 100644
    > --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
    > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
    > @@ -47,10 +47,7 @@ __invalid:
    >
    > /*
    > * x0: SMCCC function ID
    > - * x1: HYP pgd
    > - * x2: per-CPU offset
    > - * x3: HYP stack
    > - * x4: HYP vectors
    > + * x1: struct kvm_nvhe_init_params PA
    > */
    > __do_hyp_init:
    > /* Check for a stub HVC call */
    > @@ -71,10 +68,16 @@ __do_hyp_init:
    > mov x0, #SMCCC_RET_NOT_SUPPORTED
    > eret
    >
    > -1:
    > - /* Set tpidr_el2 for use by HYP to free a register */
    > - msr tpidr_el2, x2
    > +1: ldr x0, [x1, #NVHE_INIT_TPIDR_EL2]
    > + msr tpidr_el2, x0
    >
    > + ldr x0, [x1, #NVHE_INIT_STACK_PTR]
    > + mov sp, x0
    > +
    > + ldr x0, [x1, #NVHE_INIT_VECTOR_PTR]
    > + msr vbar_el2, x0
    > +
    > + ldr x1, [x1, #NVHE_INIT_PGD_PTR]
    > phys_to_ttbr x0, x1
    > alternative_if ARM64_HAS_CNP
    > orr x0, x0, #TTBR_CNP_BIT
    > @@ -134,10 +137,6 @@ alternative_else_nop_endif
    > msr sctlr_el2, x0
    > isb
    >
    > - /* Set the stack and new vectors */
    > - mov sp, x3
    > - msr vbar_el2, x4
    > -
    > /* Hello, World! */
    > mov x0, #SMCCC_RET_SUCCESS
    > eret
    > diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
    > b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
    > index e2eafe2c93af..411b0f652417 100644
    > --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
    > +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
    > @@ -14,6 +14,8 @@
    >
    > #include <kvm/arm_hypercalls.h>
    >
    > +DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
    > +
    > static void handle_host_hcall(unsigned long func_id,
    > struct kvm_cpu_context *host_ctxt)
    > {

    Thanks,

    M.
    --
    Jazz is not dead. It just smells funny...

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