[PATCH v3 09/23] kvm: arm64: Move hyp-init params to a per-CPU struct

David Brazdil
2020-11-26T15:58:40Z

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 three
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 | 6 ++++++
arch/arm64/include/asm/kvm_hyp.h | 2 +-
arch/arm64/kernel/asm-offsets.c | 3 +++
arch/arm64/kvm/arm.c | 23 +++++++++++++----------
arch/arm64/kvm/hyp/nvhe/hyp-init.S | 16 +++++++---------
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 ++
6 files changed, 32 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 531f9d04eefd..1a7b91534a16 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -148,6 +148,12 @@ extern void *__vhe_undefined_symbol;

#endif

+struct kvm_nvhe_init_params {
+ unsigned long tpidr_el2;
+ unsigned long stack_hyp_va;
+ phys_addr_t pgd_pa;
+};
+
/* 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..cb25c15e3d8d 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -14,6 +14,7 @@

DECLARE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt);
DECLARE_PER_CPU(unsigned long, kvm_hyp_vector);
+DECLARE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);

#define read_sysreg_elx(r,nvh,vh) \
({ \
@@ -98,4 +99,3 @@ void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par);
#endif

#endif /* __ARM64_KVM_HYP_H__ */
-
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 7d32fc959b1a..8d6272a01a00 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -110,6 +110,9 @@ 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_TPIDR_EL2, offsetof(struct kvm_nvhe_init_params, tpidr_el2));
+ DEFINE(NVHE_INIT_STACK_HYP_VA, offsetof(struct kvm_nvhe_init_params, stack_hyp_va));
+ DEFINE(NVHE_INIT_PGD_PA, offsetof(struct kvm_nvhe_init_params, pgd_pa));
#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 cd6e5dec203f..7b718c6c6c52 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -49,6 +49,7 @@ 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);
@@ -1353,9 +1354,7 @@ static int kvm_init_vector_slots(void)

static void cpu_init_hyp_mode(void)
{
- phys_addr_t pgd_ptr;
- unsigned long hyp_stack_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 */
@@ -1366,12 +1365,17 @@ 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);
+ params->stack_hyp_va = kern_hyp_va(__this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE);
+ params->pgd_pa = kvm_mmu_get_httbr();
+
+ /*
+ * Flush the init params from the data cache because the struct will
+ * be read while the MMU is off.
+ */
+ kvm_flush_dcache_to_poc(params, sizeof(*params));

/*
* Call initialization code, and switch to the full blown HYP code.
@@ -1380,8 +1384,7 @@ 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, &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 b3492a3c4232..77c983aa90fa 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -47,9 +47,7 @@ __invalid:

/*
* x0: SMCCC function ID
- * x1: HYP pgd
- * x2: per-CPU offset
- * x3: HYP stack
+ * x1: struct kvm_nvhe_init_params PA
*/
__do_hyp_init:
/* Check for a stub HVC call */
@@ -70,10 +68,13 @@ __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_HYP_VA]
+ mov sp, x0
+
+ ldr x1, [x1, #NVHE_INIT_PGD_PA]
phys_to_ttbr x0, x1
alternative_if ARM64_HAS_CNP
orr x0, x0, #TTBR_CNP_BIT
@@ -133,9 +134,6 @@ alternative_else_nop_endif
msr sctlr_el2, x0
isb

- /* Set the stack */
- mov sp, x3
-
/* Set the host vector */
ldr x0, =__kvm_hyp_host_vector
kimg_hyp_va x0, x1
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 82df7fc24760..a4f1cac714d7 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -16,6 +16,8 @@
#define DECLARE_REG(type, name, ctxt, reg) \
type name = (type)cpu_reg(ctxt, (reg))

+DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
+
static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1);
--
2.29.2.454.gaff20da3a2-goog