From: Rick Edgecombe <[email protected]> Sent: Wednesday, February 21, 2024 6:10 PM >
Historically, the preferred Subject prefix for changes to connection.c has been "Drivers: hv: vmbus:", not just "hv:". Sometimes that preference isn't followed, but most of the time it is. > On TDX it is possible for the untrusted host to cause I'd argue that this is for CoCo VMs in general, not just TDX. I don't know all the failure modes for SEV-SNP, but the code paths you are changing are run in both TDX and SEV-SNP CoCo VMs. > set_memory_encrypted() or set_memory_decrypted() to fail such that an > error is returned and the resulting memory is shared. Callers need to take > care to handle these errors to avoid returning decrypted (shared) memory to > the page allocator, which could lead to functional or security issues. > > Hyperv could free decrypted/shared pages if set_memory_encrypted() fails. It's not Hyper-V doing the freeing. Maybe say "VMBus code could free ...." > Leak the pages if this happens. > > Only compile tested. > > Cc: "K. Y. Srinivasan" <[email protected]> > Cc: Haiyang Zhang <[email protected]> > Cc: Wei Liu <[email protected]> > Cc: Dexuan Cui <[email protected]> > Cc: [email protected] > Signed-off-by: Rick Edgecombe <[email protected]> > --- > drivers/hv/connection.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c > index 3cabeeabb1ca..e39493421bbb 100644 > --- a/drivers/hv/connection.c > +++ b/drivers/hv/connection.c > @@ -315,6 +315,7 @@ int vmbus_connect(void) > > void vmbus_disconnect(void) > { > + int ret; > /* > * First send the unload request to the host. > */ > @@ -337,11 +338,13 @@ void vmbus_disconnect(void) > vmbus_connection.int_page = NULL; > } > > - set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[0], > 1); > - set_memory_encrypted((unsigned long)vmbus_connection.monitor_pages[1], > 1); > + ret = set_memory_encrypted((unsigned > long)vmbus_connection.monitor_pages[0], 1); > + ret |= set_memory_encrypted((unsigned > long)vmbus_connection.monitor_pages[1], 1); > > - hv_free_hyperv_page(vmbus_connection.monitor_pages[0]); > - hv_free_hyperv_page(vmbus_connection.monitor_pages[1]); > + if (!ret) { > + hv_free_hyperv_page(vmbus_connection.monitor_pages[0]); > + hv_free_hyperv_page(vmbus_connection.monitor_pages[1]); > + } Of course, this will leak the memory for both pages if only one of the set_memory_encrypted() calls fails, but I'm OK with that. It doesn't seem worth the additional complexity to treat each page separately. > vmbus_connection.monitor_pages[0] = NULL; > vmbus_connection.monitor_pages[1] = NULL; > } > -- > 2.34.1
