diff options
| author | Adin Scannell <ascannell@google.com> | 2018-06-06 23:25:26 -0700 |
|---|---|---|
| committer | Shentubot <shentubot@google.com> | 2018-06-06 23:26:14 -0700 |
| commit | d26984515900a2f88da047ee8a28ba1ca152aa58 (patch) | |
| tree | 3ba669b9d0a3cb397e1c04a888e7a45602b9370e /pkg/sentry/platform/ring0 | |
| parent | 3374849cb553fab16e69d39cf6e49f843d94790b (diff) | |
Ensure guest-mode for page table modifications.
Because of the KVM shadow page table implementation, modifications made
to guest page tables from host mode may not be syncronized correctly,
resulting in undefined behavior. This is a KVM bug: page table pages
should also be tracked for host modifications and resynced appropriately
(e.g. the guest could "DMA" into a page table page in theory).
However, since we can't rely on this being fixed everywhere, workaround
the issue by forcing page table modifications to be in guest mode. This
will generally be the case anyways, but now if an exit occurs during
modifications, we will re-enter and perform the modifications again.
PiperOrigin-RevId: 199587895
Change-Id: I83c20b4cf2a9f9fa56f59f34939601dd34538fb0
Diffstat (limited to 'pkg/sentry/platform/ring0')
| -rw-r--r-- | pkg/sentry/platform/ring0/defs_amd64.go | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/pkg/sentry/platform/ring0/defs_amd64.go b/pkg/sentry/platform/ring0/defs_amd64.go index 0d068c00a..84819f132 100644 --- a/pkg/sentry/platform/ring0/defs_amd64.go +++ b/pkg/sentry/platform/ring0/defs_amd64.go @@ -104,6 +104,14 @@ func (c *CPU) ErrorCode() (value uintptr, user bool) { return c.errorCode, c.errorType != 0 } +// ClearErrorCode resets the error code. +// +//go:nosplit +func (c *CPU) ClearErrorCode() { + c.errorCode = 0 // No code. + c.errorType = 1 // User mode. +} + // SwitchArchOpts are embedded in SwitchOpts. type SwitchArchOpts struct { // UserPCID indicates that the application PCID to be used on switch, |