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Message-ID: <be241d5b3db1ce9e5529c18ebef8c800@kernel.org>
Date: Tue, 10 Nov 2020 15:30:22 +0000
From: Marc Zyngier <maz@...nel.org>
To: David Brazdil <dbrazdil@...gle.com>
Cc: kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, James Morse <james.morse@....com>,
Julien Thierry <julien.thierry.kdev@...il.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>, Dennis Zhou <dennis@...nel.org>,
Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
Mark Rutland <mark.rutland@....com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Quentin Perret <qperret@...gle.com>,
Andrew Scull <ascull@...gle.com>,
Andrew Walbran <qwandor@...gle.com>, kernel-team@...roid.com
Subject: Re: [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@...gle.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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