From bf308242ab98b5d1648c3663e753556bef9bec01 Mon Sep 17 00:00:00 2001 From: Andre Przywara Date: Fri, 11 May 2018 15:20:14 +0100 Subject: KVM: arm/arm64: VGIC/ITS: protect kvm_read_guest() calls with SRCU lock kvm_read_guest() will eventually look up in kvm_memslots(), which requires either to hold the kvm->slots_lock or to be inside a kvm->srcu critical section. In contrast to x86 and s390 we don't take the SRCU lock on every guest exit, so we have to do it individually for each kvm_read_guest() call. Provide a wrapper which does that and use that everywhere. Note that ending the SRCU critical section before returning from the kvm_read_guest() wrapper is safe, because the data has been *copied*, so we don't need to rely on valid references to the memslot anymore. Cc: Stable # 4.8+ Reported-by: Jan Glauber Signed-off-by: Andre Przywara Acked-by: Christoffer Dall Signed-off-by: Paolo Bonzini --- arch/arm/include/asm/kvm_mmu.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/arm/include/asm') diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h index 707a1f06dc5d..f675162663f0 100644 --- a/arch/arm/include/asm/kvm_mmu.h +++ b/arch/arm/include/asm/kvm_mmu.h @@ -309,6 +309,22 @@ static inline unsigned int kvm_get_vmid_bits(void) return 8; } +/* + * We are not in the kvm->srcu critical section most of the time, so we take + * the SRCU read lock here. Since we copy the data from the user page, we + * can immediately drop the lock again. + */ +static inline int kvm_read_guest_lock(struct kvm *kvm, + gpa_t gpa, void *data, unsigned long len) +{ + int srcu_idx = srcu_read_lock(&kvm->srcu); + int ret = kvm_read_guest(kvm, gpa, data, len); + + srcu_read_unlock(&kvm->srcu, srcu_idx); + + return ret; +} + static inline void *kvm_get_hyp_vector(void) { return kvm_ksym_ref(__kvm_hyp_vector); -- cgit v1.2.3