kvm: prefault a floating point state before restoring it

If physical pages of a memory region are not mapped yet, the kernel will
trigger KVM_EXIT_MMIO and we will map physical pages in bluepillHandler().

An instruction that triggered a fault will not be re-executed, it
will be emulated in the kernel, but it can't  emulate complex
instructions like xsave, xrstor. We can touch the memory with
simple instructions to workaround this problem.

1 files changed, 4 insertions, 4 deletions

diff --git a/pkg/sentry/arch/arch_aarch64.go b/pkg/sentry/arch/arch_aarch64.go
index fd73751e7..6b81e9708 100644
--- a/pkg/sentry/arch/arch_aarch64.go
+++ b/pkg/sentry/arch/arch_aarch64.go
@@ -88,15 +88,15 @@ func (f aarch64FPState) fork() aarch64FPState {
 }
 
 // FloatingPointData returns the raw data pointer.
-func (f aarch64FPState) FloatingPointData() *FloatingPointData {
-	return (*FloatingPointData)(&f[0])
+func (f aarch64FPState) FloatingPointData() FloatingPointData {
+	return ([]byte)(f)
 }
 
 // NewFloatingPointData returns a new floating point data blob.
 //
 // This is primarily for use in tests.
-func NewFloatingPointData() *FloatingPointData {
-	return (*FloatingPointData)(&(newAarch64FPState()[0]))
+func NewFloatingPointData() FloatingPointData {
+	return ([]byte)(newAarch64FPState())
 }
 
 // State contains the common architecture bits for aarch64 (the build tag of this