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Merge branch 'kvm-dwmw2-fixes' into HEAD

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This brings in a few important fixes for Xen emulation.
While nobody should be enabling it, the bug effectively
allows userspace to read arbitrary memory.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2022-11-23 18:52:29 -05:00
commit fe08e36be9
2 changed files with 29 additions and 10 deletions
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32
arch/x86/kvm/xen.c
View File

@ -954,6 +954,14 @@ static int kvm_xen_hypercall_complete_userspace(struct kvm_vcpu *vcpu)
return kvm_xen_hypercall_set_result(vcpu, run->xen.u.hcall.result);
}
static inline int max_evtchn_port(struct kvm *kvm)
{
if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode)
return EVTCHN_2L_NR_CHANNELS;
else
return COMPAT_EVTCHN_2L_NR_CHANNELS;
}
static bool wait_pending_event(struct kvm_vcpu *vcpu, int nr_ports,
evtchn_port_t *ports)
{
@ -1042,6 +1050,10 @@ static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode,
*r = -EFAULT;
goto out;
}
if (ports[i] >= max_evtchn_port(vcpu->kvm)) {
*r = -EINVAL;
goto out;
}
}
if (sched_poll.nr_ports == 1)
@ -1215,6 +1227,7 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
bool longmode;
u64 input, params[6], r = -ENOSYS;
bool handled = false;
u8 cpl;
input = (u64)kvm_register_read(vcpu, VCPU_REGS_RAX);
@ -1242,9 +1255,17 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
params[5] = (u64)kvm_r9_read(vcpu);
}
#endif
cpl = static_call(kvm_x86_get_cpl)(vcpu);
trace_kvm_xen_hypercall(input, params[0], params[1], params[2],
params[3], params[4], params[5]);
/*
* Only allow hypercall acceleration for CPL0. The rare hypercalls that
* are permitted in guest userspace can be handled by the VMM.
*/
if (unlikely(cpl > 0))
goto handle_in_userspace;
switch (input) {
case __HYPERVISOR_xen_version:
if (params[0] == XENVER_version && vcpu->kvm->arch.xen.xen_version) {
@ -1279,10 +1300,11 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
if (handled)
return kvm_xen_hypercall_set_result(vcpu, r);
handle_in_userspace:
vcpu->run->exit_reason = KVM_EXIT_XEN;
vcpu->run->xen.type = KVM_EXIT_XEN_HCALL;
vcpu->run->xen.u.hcall.longmode = longmode;
vcpu->run->xen.u.hcall.cpl = static_call(kvm_x86_get_cpl)(vcpu);
vcpu->run->xen.u.hcall.cpl = cpl;
vcpu->run->xen.u.hcall.input = input;
vcpu->run->xen.u.hcall.params[0] = params[0];
vcpu->run->xen.u.hcall.params[1] = params[1];
@ -1297,14 +1319,6 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
return 0;
}
static inline int max_evtchn_port(struct kvm *kvm)
{
if (IS_ENABLED(CONFIG_64BIT) && kvm->arch.xen.long_mode)
return EVTCHN_2L_NR_CHANNELS;
else
return COMPAT_EVTCHN_2L_NR_CHANNELS;
}
static void kvm_xen_check_poller(struct kvm_vcpu *vcpu, int port)
{
int poll_evtchn = vcpu->arch.xen.poll_evtchn;

7
virt/kvm/pfncache.c
View File

@ -297,7 +297,12 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc,
if (!gpc->valid || old_uhva != gpc->uhva) {
ret = hva_to_pfn_retry(kvm, gpc);
} else {
/* If the HVA→PFN mapping was already valid, don't unmap it. */
/*
* If the HVA→PFN mapping was already valid, don't unmap it.
* But do update gpc->khva because the offset within the page
* may have changed.
*/
gpc->khva = old_khva + page_offset;
old_pfn = KVM_PFN_ERR_FAULT;
old_khva = NULL;
ret = 0;