@@ -3973,7 +3973,21 @@ static void hvm_s3_resume(struct domain *d)
}
}
-bool hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
+static void do_flush(void *data)
+{
+ cpumask_t *mask = data;
+ unsigned int cpu = smp_processor_id();
+
+ ASSERT(cpumask_test_cpu(cpu, mask));
+ /*
+ * A vmexit/vmenter (caused by the IPI issued to execute this function) is
+ * enough to force a TLB flush since we have already ticked the vCPU ASID
+ * prior to issuing the IPI.
+ */
+ cpumask_clear_cpu(cpu, mask);
+}
+
+void hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
void *ctxt)
{
static DEFINE_PER_CPU(cpumask_t, flush_cpumask);
@@ -3981,27 +3995,8 @@ bool hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
struct domain *d = current->domain;
struct vcpu *v;
- /* Avoid deadlock if more than one vcpu tries this at the same time. */
- if ( !spin_trylock(&d->hypercall_deadlock_mutex) )
- return false;
-
- /* Pause all other vcpus. */
- for_each_vcpu ( d, v )
- if ( v != current && flush_vcpu(ctxt, v) )
- vcpu_pause_nosync(v);
-
- /* Now that all VCPUs are signalled to deschedule, we wait... */
- for_each_vcpu ( d, v )
- if ( v != current && flush_vcpu(ctxt, v) )
- while ( !vcpu_runnable(v) && v->is_running )
- cpu_relax();
-
- /* All other vcpus are paused, safe to unlock now. */
- spin_unlock(&d->hypercall_deadlock_mutex);
-
cpumask_clear(mask);
- /* Flush paging-mode soft state (e.g., va->gfn cache; PAE PDPE cache). */
for_each_vcpu ( d, v )
{
unsigned int cpu;
@@ -4009,22 +4004,17 @@ bool hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
if ( !flush_vcpu(ctxt, v) )
continue;
- paging_update_cr3(v, false);
+ hvm_asid_flush_vcpu(v);
cpu = read_atomic(&v->dirty_cpu);
- if ( is_vcpu_dirty_cpu(cpu) )
+ if ( cpu != smp_processor_id() && is_vcpu_dirty_cpu(cpu) )
__cpumask_set_cpu(cpu, mask);
}
- /* Flush TLBs on all CPUs with dirty vcpu state. */
- flush_tlb_mask(mask);
+ on_selected_cpus(mask, do_flush, mask, 0);
- /* Done. */
- for_each_vcpu ( d, v )
- if ( v != current && flush_vcpu(ctxt, v) )
- vcpu_unpause(v);
-
- return true;
+ while ( !cpumask_empty(mask) )
+ cpu_relax();
}
static bool always_flush(void *ctxt, struct vcpu *v)
@@ -4037,7 +4027,9 @@ static int hvmop_flush_tlb_all(void)
if ( !is_hvm_domain(current->domain) )
return -EINVAL;
- return hvm_flush_vcpu_tlb(always_flush, NULL) ? 0 : -ERESTART;
+ hvm_flush_vcpu_tlb(always_flush, NULL);
+
+ return 0;
}
static int hvmop_set_evtchn_upcall_vector(
@@ -604,12 +604,7 @@ int viridian_hypercall(struct cpu_user_regs *regs)
if ( input_params.flags & HV_FLUSH_ALL_PROCESSORS )
input_params.vcpu_mask = ~0ul;
- /*
- * A false return means that another vcpu is currently trying
- * a similar operation, so back off.
- */
- if ( !hvm_flush_vcpu_tlb(need_flush, &input_params.vcpu_mask) )
- return HVM_HCALL_preempted;
+ hvm_flush_vcpu_tlb(need_flush, &input_params.vcpu_mask);
output.rep_complete = input.rep_count;
@@ -333,7 +333,7 @@ const char *hvm_efer_valid(const struct vcpu *v, uint64_t value,
signed int cr0_pg);
unsigned long hvm_cr4_guest_valid_bits(const struct domain *d, bool restore);
-bool hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
+void hvm_flush_vcpu_tlb(bool (*flush_vcpu)(void *ctxt, struct vcpu *v),
void *ctxt);
#ifdef CONFIG_HVM
Current implementation of hvm_flush_vcpu_tlb is highly inefficient. First of all the call to flush_tlb_mask is completely useless when trying to flush the TLB of HVM guests, as this TLB flush is executed in root mode, and hence doesn't flush any guest state cache. Secondly, calling paging_update_cr3 albeit correct, is much more expensive than strictly required. Instead a TLB flush can be achieved by calling hvm_asid_flush_vcpu on each pCPU that has a domain vCPU state currently loaded. This call will invalidate the current non-root context, thus forcing a clean cache state on vmentry. If the guest is not using ASIDs, the vmexit caused by the on_selected_cpus IPI will already force a TLB flush. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> --- xen/arch/x86/hvm/hvm.c | 54 ++++++++++++---------------- xen/arch/x86/hvm/viridian/viridian.c | 7 +--- xen/include/asm-x86/hvm/hvm.h | 2 +- 3 files changed, 25 insertions(+), 38 deletions(-)