From 92c58965e9656dc6e682a8ffe520fac0fb256d13 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 26 Dec 2022 12:03:16 +0000 Subject: KVM: x86/xen: Use kvm_read_guest_virt() instead of open-coding it badly In particular, we shouldn't assume that being contiguous in guest virtual address space means being contiguous in guest *physical* address space. In dropping the manual calls to kvm_mmu_gva_to_gpa_system(), also drop the srcu_read_lock() that was around them. All call sites are reached from kvm_xen_hypercall() which is called from the handle_exit function with the read lock already held. 536395260 ("KVM: x86/xen: handle PV timers oneshot mode") 1a65105a5 ("KVM: x86/xen: handle PV spinlocks slowpath") Fixes: 2fd6df2f2 ("KVM: x86/xen: intercept EVTCHNOP_send from guests") Signed-off-by: David Woodhouse Message-Id: <20221226120320.1125390-2-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/xen.c | 56 ++++++++++++++++++------------------------------------ 1 file changed, 18 insertions(+), 38 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index d1a98d834d18..929b887eafd7 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -1184,30 +1184,22 @@ static bool wait_pending_event(struct kvm_vcpu *vcpu, int nr_ports, static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode, u64 param, u64 *r) { - int idx, i; struct sched_poll sched_poll; evtchn_port_t port, *ports; - gpa_t gpa; + struct x86_exception e; + int i; if (!lapic_in_kernel(vcpu) || !(vcpu->kvm->arch.xen_hvm_config.flags & KVM_XEN_HVM_CONFIG_EVTCHN_SEND)) return false; - idx = srcu_read_lock(&vcpu->kvm->srcu); - gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL); - srcu_read_unlock(&vcpu->kvm->srcu, idx); - if (!gpa) { - *r = -EFAULT; - return true; - } - if (IS_ENABLED(CONFIG_64BIT) && !longmode) { struct compat_sched_poll sp32; /* Sanity check that the compat struct definition is correct */ BUILD_BUG_ON(sizeof(sp32) != 16); - if (kvm_vcpu_read_guest(vcpu, gpa, &sp32, sizeof(sp32))) { + if (kvm_read_guest_virt(vcpu, param, &sp32, sizeof(sp32), &e)) { *r = -EFAULT; return true; } @@ -1221,8 +1213,8 @@ static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode, sched_poll.nr_ports = sp32.nr_ports; sched_poll.timeout = sp32.timeout; } else { - if (kvm_vcpu_read_guest(vcpu, gpa, &sched_poll, - sizeof(sched_poll))) { + if (kvm_read_guest_virt(vcpu, param, &sched_poll, + sizeof(sched_poll), &e)) { *r = -EFAULT; return true; } @@ -1244,18 +1236,13 @@ static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode, } else ports = &port; + if (kvm_read_guest_virt(vcpu, (gva_t)sched_poll.ports, ports, + sched_poll.nr_ports * sizeof(*ports), &e)) { + *r = -EFAULT; + return true; + } + for (i = 0; i < sched_poll.nr_ports; i++) { - idx = srcu_read_lock(&vcpu->kvm->srcu); - gpa = kvm_mmu_gva_to_gpa_system(vcpu, - (gva_t)(sched_poll.ports + i), - NULL); - srcu_read_unlock(&vcpu->kvm->srcu, idx); - - if (!gpa || kvm_vcpu_read_guest(vcpu, gpa, - &ports[i], sizeof(port))) { - *r = -EFAULT; - goto out; - } if (ports[i] >= max_evtchn_port(vcpu->kvm)) { *r = -EINVAL; goto out; @@ -1331,9 +1318,8 @@ static bool kvm_xen_hcall_vcpu_op(struct kvm_vcpu *vcpu, bool longmode, int cmd, int vcpu_id, u64 param, u64 *r) { struct vcpu_set_singleshot_timer oneshot; + struct x86_exception e; s64 delta; - gpa_t gpa; - int idx; if (!kvm_xen_timer_enabled(vcpu)) return false; @@ -1344,9 +1330,6 @@ static bool kvm_xen_hcall_vcpu_op(struct kvm_vcpu *vcpu, bool longmode, int cmd, *r = -EINVAL; return true; } - idx = srcu_read_lock(&vcpu->kvm->srcu); - gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL); - srcu_read_unlock(&vcpu->kvm->srcu, idx); /* * The only difference for 32-bit compat is the 4 bytes of @@ -1364,9 +1347,8 @@ static bool kvm_xen_hcall_vcpu_op(struct kvm_vcpu *vcpu, bool longmode, int cmd, BUILD_BUG_ON(sizeof_field(struct compat_vcpu_set_singleshot_timer, flags) != sizeof_field(struct vcpu_set_singleshot_timer, flags)); - if (!gpa || - kvm_vcpu_read_guest(vcpu, gpa, &oneshot, longmode ? sizeof(oneshot) : - sizeof(struct compat_vcpu_set_singleshot_timer))) { + if (kvm_read_guest_virt(vcpu, param, &oneshot, longmode ? sizeof(oneshot) : + sizeof(struct compat_vcpu_set_singleshot_timer), &e)) { *r = -EFAULT; return true; } @@ -2003,14 +1985,12 @@ static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r) { struct evtchnfd *evtchnfd; struct evtchn_send send; - gpa_t gpa; - int idx; + struct x86_exception e; - idx = srcu_read_lock(&vcpu->kvm->srcu); - gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL); - srcu_read_unlock(&vcpu->kvm->srcu, idx); + /* Sanity check: this structure is the same for 32-bit and 64-bit */ + BUILD_BUG_ON(sizeof(send) != 4); - if (!gpa || kvm_vcpu_read_guest(vcpu, gpa, &send, sizeof(send))) { + if (kvm_read_guest_virt(vcpu, param, &send, sizeof(send), &e)) { *r = -EFAULT; return true; } -- cgit v1.2.3