[PATCH v2 03/12] KVM: arm64: Pass pointer to __pkvm_init_switch_pgd

[Pierre-Clément Tosi]

Make the function take a VA pointer, instead of a phys_addr_t, to fully
take advantage of the high-level C language and its type checker.

Perform all accesses to the kvm_nvhe_init_params before disabling the
MMU, removing the need to access it using physical addresses, which was
the reason for taking a phys_addr_t.

Signed-off-by: Pierre-Clément Tosi <ptosi at google.com>
---
 arch/arm64/include/asm/kvm_hyp.h   |  3 ++-
 arch/arm64/kvm/hyp/nvhe/hyp-init.S | 12 +++++++++---
 arch/arm64/kvm/hyp/nvhe/setup.c    |  4 +---
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 96daf7cf6802..c195e71d0746 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -123,7 +123,8 @@ void __noreturn __hyp_do_panic(struct kvm_cpu_context *host_ctxt, u64 spsr,
 #endif
 
 #ifdef __KVM_NVHE_HYPERVISOR__
-void __pkvm_init_switch_pgd(phys_addr_t params, void (*finalize_fn)(void));
+void __pkvm_init_switch_pgd(struct kvm_nvhe_init_params *params,
+			    void (*finalize_fn)(void));
 int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
 		unsigned long *per_cpu_base, u32 hyp_va_bits);
 void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index 2994878d68ea..5a15737b4233 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -265,7 +265,15 @@ alternative_else_nop_endif
 
 SYM_CODE_END(__kvm_handle_stub_hvc)
 
+/*
+ * void __pkvm_init_switch_pgd(struct kvm_nvhe_init_params *params,
+ *                             void (*finalize_fn)(void));
+ */
 SYM_FUNC_START(__pkvm_init_switch_pgd)
+	/* Load the inputs from the VA pointer before turning the MMU off */
+	ldr	x5, [x0, #NVHE_INIT_PGD_PA]
+	ldr	x0, [x0, #NVHE_INIT_STACK_HYP_VA]
+
 	/* Turn the MMU off */
 	pre_disable_mmu_workaround
 	mrs	x2, sctlr_el2
@@ -276,15 +284,13 @@ SYM_FUNC_START(__pkvm_init_switch_pgd)
 	tlbi	alle2
 
 	/* Install the new pgtables */
-	ldr	x3, [x0, #NVHE_INIT_PGD_PA]
-	phys_to_ttbr x4, x3
+	phys_to_ttbr x4, x5
 alternative_if ARM64_HAS_CNP
 	orr	x4, x4, #TTBR_CNP_BIT
 alternative_else_nop_endif
 	msr	ttbr0_el2, x4
 
 	/* Set the new stack pointer */
-	ldr	x0, [x0, #NVHE_INIT_STACK_HYP_VA]
 	mov	sp, x0
 
 	/* And turn the MMU back on! */
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index bcaeb0fafd2d..45b83f3ed012 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -314,7 +314,6 @@ void __noreturn __pkvm_init_finalise(void)
 int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
 		unsigned long *per_cpu_base, u32 hyp_va_bits)
 {
-	struct kvm_nvhe_init_params *params;
 	void *virt = hyp_phys_to_virt(phys);
 	typeof(__pkvm_init_switch_pgd) *fn;
 	int ret;
@@ -338,9 +337,8 @@ int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
 	update_nvhe_init_params();
 
 	/* Jump in the idmap page to switch to the new page-tables */
-	params = this_cpu_ptr(&kvm_init_params);
 	fn = (typeof(fn))__hyp_pa(__pkvm_init_switch_pgd);
-	fn(__hyp_pa(params), __pkvm_init_finalise);
+	fn(this_cpu_ptr(&kvm_init_params), __pkvm_init_finalise);
 
 	unreachable();
 }
-- 
2.44.0.478.gd926399ef9-goog


-- 
Pierre