Commit ea9d7c83 authored by Pierre-Clément Tosi's avatar Pierre-Clément Tosi Committed by Oliver Upton
Browse files

KVM: arm64: Fix __pkvm_init_switch_pgd call ABI 



Fix the mismatch between the (incorrect) C signature, C call site, and
asm implementation by aligning all three on an API passing the
parameters (pgd and SP) separately, instead of as a bundled struct.

Remove the now unnecessary memory accesses while the MMU is off from the
asm, which simplifies the C caller (as it does not need to convert a VA
struct pointer to PA) and makes the code slightly more robust by
offsetting the struct fields from C and properly expressing the call to
the C compiler (e.g. type checker and kCFI).

Fixes: f320bc74 ("KVM: arm64: Prepare the creation of s1 mappings at EL2")
Signed-off-by: default avatarPierre-Clément Tosi <ptosi@google.com>
Acked-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20240610063244.2828978-3-ptosi@google.com


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent a8f06558

arch/arm64/include/asm/kvm_hyp.h

+2 −2
Original line number Diff line number Diff line
@@ -124,8 +124,8 @@ 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 phys, unsigned long size,

			    phys_addr_t pgd, void *sp, void *cont_fn);

void __pkvm_init_switch_pgd(phys_addr_t pgd, unsigned long sp,

		void (*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);

arch/arm64/kvm/hyp/nvhe/hyp-init.S

+13 −11
Original line number Diff line number Diff line
@@ -265,33 +265,35 @@ alternative_else_nop_endif 


SYM_CODE_END(__kvm_handle_stub_hvc)



/*

 * void __pkvm_init_switch_pgd(phys_addr_t pgd, unsigned long sp,

 *                             void (*fn)(void));

 */

SYM_FUNC_START(__pkvm_init_switch_pgd)

	/* Turn the MMU off */

	pre_disable_mmu_workaround

	mrs	x2, sctlr_el2

	bic	x3, x2, #SCTLR_ELx_M

	msr	sctlr_el2, x3

	mrs	x3, sctlr_el2

	bic	x4, x3, #SCTLR_ELx_M

	msr	sctlr_el2, x4

	isb



	tlbi	alle2



	/* Install the new pgtables */

	ldr	x3, [x0, #NVHE_INIT_PGD_PA]

	phys_to_ttbr x4, x3

	phys_to_ttbr x5, x0

alternative_if ARM64_HAS_CNP

	orr	x4, x4, #TTBR_CNP_BIT

	orr	x5, x5, #TTBR_CNP_BIT

alternative_else_nop_endif

	msr	ttbr0_el2, x4

	msr	ttbr0_el2, x5



	/* Set the new stack pointer */

	ldr	x0, [x0, #NVHE_INIT_STACK_HYP_VA]

	mov	sp, x0

	mov	sp, x1



	/* And turn the MMU back on! */

	dsb	nsh

	isb

	set_sctlr_el2	x2

	ret	x1

	set_sctlr_el2	x3

	ret	x2

SYM_FUNC_END(__pkvm_init_switch_pgd)



	.popsection

arch/arm64/kvm/hyp/nvhe/setup.c

+2 −2
Original line number Diff line number Diff line
@@ -339,7 +339,7 @@ int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus, 
{

	struct kvm_nvhe_init_params *params;

	void *virt = hyp_phys_to_virt(phys);

	void (*fn)(phys_addr_t params_pa, void *finalize_fn_va);

	typeof(__pkvm_init_switch_pgd) *fn;

	int ret;



	BUG_ON(kvm_check_pvm_sysreg_table());
@@ -363,7 +363,7 @@ int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus, 
	/* 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(params->pgd_pa, params->stack_hyp_va, __pkvm_init_finalise);



	unreachable();

}