diff options
| -rw-r--r-- | pkg/ring0/pagetables/pagetables.go | 9 | ||||
| -rw-r--r-- | pkg/sentry/platform/kvm/machine_amd64.go | 4 |
2 files changed, 13 insertions, 0 deletions
diff --git a/pkg/ring0/pagetables/pagetables.go b/pkg/ring0/pagetables/pagetables.go index 3f17fba49..9dac53c80 100644 --- a/pkg/ring0/pagetables/pagetables.go +++ b/pkg/ring0/pagetables/pagetables.go @@ -322,3 +322,12 @@ func (p *PageTables) Lookup(addr hostarch.Addr, findFirst bool) (virtual hostarc func (p *PageTables) MarkReadOnlyShared() { p.readOnlyShared = true } + +// PrefaultRootTable touches the root table page to be sure that its physical +// pages are mapped. +// +//go:nosplit +//go:noinline +func (p *PageTables) PrefaultRootTable() PTE { + return p.root[0] +} diff --git a/pkg/sentry/platform/kvm/machine_amd64.go b/pkg/sentry/platform/kvm/machine_amd64.go index d7abfefb4..f727e61b0 100644 --- a/pkg/sentry/platform/kvm/machine_amd64.go +++ b/pkg/sentry/platform/kvm/machine_amd64.go @@ -351,6 +351,10 @@ func (c *vCPU) SwitchToUser(switchOpts ring0.SwitchOpts, info *arch.SignalInfo) // allocations occur. entersyscall() bluepill(c) + // The root table physical page has to be mapped to not fault in iret + // or sysret after switching into a user address space. sysret and + // iret are in the upper half that is global and already mapped. + switchOpts.PageTables.PrefaultRootTable() prefaultFloatingPointState(switchOpts.FloatingPointState) vector = c.CPU.SwitchToUser(switchOpts) exitsyscall() |