Commit 6e3bfbb2 authored by Andrew Scull's avatar Andrew Scull Committed by Marc Zyngier
Browse files

KVM: arm64: nVHE: Use separate vector for the host 



The host is treated differently from the guests when an exception is
taken so introduce a separate vector that is specialized for the host.
This also allows the nVHE specific code to move out of hyp-entry.S and
into nvhe/host.S.

The host is only expected to make HVC calls and anything else is
considered invalid and results in a panic.

Hyp initialization is now passed the vector that is used for the host
and it is swapped for the guest vector during the context switch.

Signed-off-by: default avatarAndrew Scull <ascull@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200915104643.2543892-7-ascull@google.com
parent a0e47952

arch/arm64/include/asm/kvm_asm.h

+2 −0
Original line number Diff line number Diff line
@@ -111,8 +111,10 @@ struct kvm_vcpu; 
struct kvm_s2_mmu;



DECLARE_KVM_NVHE_SYM(__kvm_hyp_init);

DECLARE_KVM_NVHE_SYM(__kvm_hyp_host_vector);

DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);

#define __kvm_hyp_init		CHOOSE_NVHE_SYM(__kvm_hyp_init)

#define __kvm_hyp_host_vector	CHOOSE_NVHE_SYM(__kvm_hyp_host_vector)

#define __kvm_hyp_vector	CHOOSE_HYP_SYM(__kvm_hyp_vector)



#ifdef CONFIG_KVM_INDIRECT_VECTORS

arch/arm64/kernel/image-vars.h

+1 −0
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ KVM_NVHE_ALIAS(kvm_update_va_mask); 
/* Global kernel state accessed by nVHE hyp code. */

KVM_NVHE_ALIAS(arm64_ssbd_callback_required);

KVM_NVHE_ALIAS(kvm_host_data);

KVM_NVHE_ALIAS(kvm_hyp_vector);

KVM_NVHE_ALIAS(kvm_vgic_global_state);



/* Kernel constant needed to compute idmap addresses. */

arch/arm64/kvm/arm.c

+10 −1
Original line number Diff line number Diff line
@@ -1277,7 +1277,7 @@ static void cpu_init_hyp_mode(void) 


	pgd_ptr = kvm_mmu_get_httbr();

	hyp_stack_ptr = __this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE;

	vector_ptr = __this_cpu_read(kvm_hyp_vector);

	vector_ptr = (unsigned long)kern_hyp_va(kvm_ksym_ref(__kvm_hyp_host_vector));



	/*

	 * Call initialization code, and switch to the full blown HYP code.
@@ -1542,6 +1542,7 @@ static int init_hyp_mode(void) 


	for_each_possible_cpu(cpu) {

		struct kvm_host_data *cpu_data;

		unsigned long *vector;



		cpu_data = per_cpu_ptr(&kvm_host_data, cpu);

		err = create_hyp_mappings(cpu_data, cpu_data + 1, PAGE_HYP);
@@ -1550,6 +1551,14 @@ static int init_hyp_mode(void) 
			kvm_err("Cannot map host CPU state: %d\n", err);

			goto out_err;

		}



		vector = per_cpu_ptr(&kvm_hyp_vector, cpu);

		err = create_hyp_mappings(vector, vector + 1, PAGE_HYP);



		if (err) {

			kvm_err("Cannot map hyp guest vector address\n");

			goto out_err;

		}

	}



	err = hyp_map_aux_data();

arch/arm64/kvm/hyp/hyp-entry.S

+0 −66
Original line number Diff line number Diff line
@@ -12,7 +12,6 @@ 
#include <asm/cpufeature.h>

#include <asm/kvm_arm.h>

#include <asm/kvm_asm.h>

#include <asm/kvm_mmu.h>

#include <asm/mmu.h>



.macro save_caller_saved_regs_vect
@@ -41,20 +40,6 @@ 


	.text



.macro do_el2_call

	/*

	 * Shuffle the parameters before calling the function

	 * pointed to in x0. Assumes parameters in x[1,2,3].

	 */

	str	lr, [sp, #-16]!

	mov	lr, x0

	mov	x0, x1

	mov	x1, x2

	mov	x2, x3

	blr	lr

	ldr	lr, [sp], #16

.endm



el1_sync:				// Guest trapped into EL2



	mrs	x0, esr_el2
@@ -63,44 +48,6 @@ el1_sync: // Guest trapped into EL2 
	ccmp	x0, #ESR_ELx_EC_HVC32, #4, ne

	b.ne	el1_trap



#ifdef __KVM_NVHE_HYPERVISOR__

	mrs	x1, vttbr_el2		// If vttbr is valid, the guest

	cbnz	x1, el1_hvc_guest	// called HVC



	/* Here, we're pretty sure the host called HVC. */

	ldp	x0, x1, [sp], #16



	/* Check for a stub HVC call */

	cmp	x0, #HVC_STUB_HCALL_NR

	b.hs	1f



	/*

	 * Compute the idmap address of __kvm_handle_stub_hvc and

	 * jump there. Since we use kimage_voffset, do not use the

	 * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead

	 * (by loading it from the constant pool).

	 *

	 * Preserve x0-x4, which may contain stub parameters.

	 */

	ldr	x5, =__kvm_handle_stub_hvc

	ldr_l	x6, kimage_voffset



	/* x5 = __pa(x5) */

	sub	x5, x5, x6

	br	x5



1:

	/*

	 * Perform the EL2 call

	 */

	kern_hyp_va	x0

	do_el2_call



	eret

	sb

#endif /* __KVM_NVHE_HYPERVISOR__ */



el1_hvc_guest:

	/*

	 * Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1.

	 * The workaround has already been applied on the host,
@@ -198,18 +145,6 @@ el2_error: 
	eret

	sb



#ifdef __KVM_NVHE_HYPERVISOR__

SYM_FUNC_START(__hyp_do_panic)

	mov	lr, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT |\

		      PSR_MODE_EL1h)

	msr	spsr_el2, lr

	ldr	lr, =panic

	msr	elr_el2, lr

	eret

	sb

SYM_FUNC_END(__hyp_do_panic)

#endif



.macro invalid_vector	label, target = hyp_panic

	.align	2

SYM_CODE_START(\label)
@@ -222,7 +157,6 @@ SYM_CODE_END(\label) 
	invalid_vector	el2t_irq_invalid

	invalid_vector	el2t_fiq_invalid

	invalid_vector	el2t_error_invalid

	invalid_vector	el2h_sync_invalid

	invalid_vector	el2h_irq_invalid

	invalid_vector	el2h_fiq_invalid

	invalid_vector	el1_fiq_invalid

arch/arm64/kvm/hyp/nvhe/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 
asflags-y := -D__KVM_NVHE_HYPERVISOR__

ccflags-y := -D__KVM_NVHE_HYPERVISOR__



obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o

obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o

obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \

	 ../fpsimd.o ../hyp-entry.o