Commit 73f38ef2 authored by Will Deacon's avatar Will Deacon Committed by Marc Zyngier
Browse files

KVM: arm64: Maintain a copy of 'kvm_arm_vmid_bits' at EL2 



Sharing 'kvm_arm_vmid_bits' between EL1 and EL2 allows the host to
modify the variable arbitrarily, potentially leading to all sorts of
shenanians as this is used to configure the VTTBR register for the
guest stage-2.

In preparation for unmapping host sections entirely from EL2, maintain
a copy of 'kvm_arm_vmid_bits' in the pKVM hypervisor and initialise it
from the host value while it is still trusted.

Tested-by: default avatarVincent Donnefort <vdonnefort@google.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-23-will@kernel.org
parent fe41a7f8

arch/arm64/include/asm/kvm_hyp.h

+2 −0
Original line number Diff line number Diff line
@@ -124,4 +124,6 @@ extern u64 kvm_nvhe_sym(id_aa64mmfr1_el1_sys_val); 
extern u64 kvm_nvhe_sym(id_aa64mmfr2_el1_sys_val);



extern unsigned long kvm_nvhe_sym(__icache_flags);

extern unsigned int kvm_nvhe_sym(kvm_arm_vmid_bits);



#endif /* __ARM64_KVM_HYP_H__ */

arch/arm64/kernel/image-vars.h

+0 −3
Original line number Diff line number Diff line
@@ -71,9 +71,6 @@ KVM_NVHE_ALIAS(nvhe_hyp_panic_handler); 
/* Vectors installed by hyp-init on reset HVC. */

KVM_NVHE_ALIAS(__hyp_stub_vectors);



/* VMID bits set by the KVM VMID allocator */

KVM_NVHE_ALIAS(kvm_arm_vmid_bits);



/* Static keys which are set if a vGIC trap should be handled in hyp. */

KVM_NVHE_ALIAS(vgic_v2_cpuif_trap);

KVM_NVHE_ALIAS(vgic_v3_cpuif_trap);

arch/arm64/kvm/arm.c

+1 −0
Original line number Diff line number Diff line
@@ -1893,6 +1893,7 @@ static void kvm_hyp_init_symbols(void) 
	kvm_nvhe_sym(id_aa64mmfr1_el1_sys_val) = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1);

	kvm_nvhe_sym(id_aa64mmfr2_el1_sys_val) = read_sanitised_ftr_reg(SYS_ID_AA64MMFR2_EL1);

	kvm_nvhe_sym(__icache_flags) = __icache_flags;

	kvm_nvhe_sym(kvm_arm_vmid_bits) = kvm_arm_vmid_bits;

}



static int kvm_hyp_init_protection(u32 hyp_va_bits)

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

+3 −0
Original line number Diff line number Diff line
@@ -15,6 +15,9 @@ 
/* Used by icache_is_vpipt(). */

unsigned long __icache_flags;



/* Used by kvm_get_vttbr(). */

unsigned int kvm_arm_vmid_bits;



/*

 * Set trap register values based on features in ID_AA64PFR0.

 */