| Message ID | 20250409000835.285105-2-romank@linux.microsoft.com |
|---|---|
| State | New |
| Headers | show |
| Series | [hyperv-next,1/6] Documentation: hyperv: Confidential VMBus | expand |
On 4/10/2025 9:54 AM, ALOK TIWARI wrote: > > [...] > > typo trsuted -> trusted > >> +To support confidential communication with the paravisor, a VmBus client >> +will first attempt to use regular, non-isolated mechanisms for >> communication. >> +To do this, it must: > Thanks for your help with this patch, and the other ones!! I'll make sure to use the spellchecker on the patches before sending another version out. > > Thanks, > Alok
On Tue, Apr 08, 2025 at 05:08:30PM -0700, Roman Kisel wrote: > Define what the confidential VMBus is and describe what advantages > it offers on the capable hardware. > > Signed-off-by: Roman Kisel <romank@linux.microsoft.com> > --- > Documentation/virt/hyperv/vmbus.rst | 41 +++++++++++++++++++++++++++++ > 1 file changed, 41 insertions(+) > > diff --git a/Documentation/virt/hyperv/vmbus.rst b/Documentation/virt/hyperv/vmbus.rst > index 1dcef6a7fda3..f600e3d09800 100644 > --- a/Documentation/virt/hyperv/vmbus.rst > +++ b/Documentation/virt/hyperv/vmbus.rst > @@ -324,3 +324,44 @@ rescinded, neither Hyper-V nor Linux retains any state about > its previous existence. Such a device might be re-added later, > in which case it is treated as an entirely new device. See > vmbus_onoffer_rescind(). > + > +Confidential VMBus > +------------------ > + > +The confidential VMBus provides the control and data planes where > +the guest doesn't talk to either the hypervisor or the host. Instead, > +it relies on the trusted paravisor. The hardware (SNP or TDX) encrypts > +the guest memory and the register state also measuring the paravisor > +image via using the platform security processor to ensure trsuted and > +confidential computing. > + > +To support confidential communication with the paravisor, a VmBus client Please be consistent. In this document I see VMBus and VmBus. We should stick with only one form. Wei.
diff --git a/Documentation/virt/hyperv/vmbus.rst b/Documentation/virt/hyperv/vmbus.rst index 1dcef6a7fda3..f600e3d09800 100644 --- a/Documentation/virt/hyperv/vmbus.rst +++ b/Documentation/virt/hyperv/vmbus.rst @@ -324,3 +324,44 @@ rescinded, neither Hyper-V nor Linux retains any state about its previous existence. Such a device might be re-added later, in which case it is treated as an entirely new device. See vmbus_onoffer_rescind(). + +Confidential VMBus +------------------ + +The confidential VMBus provides the control and data planes where +the guest doesn't talk to either the hypervisor or the host. Instead, +it relies on the trusted paravisor. The hardware (SNP or TDX) encrypts +the guest memory and the register state also measuring the paravisor +image via using the platform security processor to ensure trsuted and +confidential computing. + +To support confidential communication with the paravisor, a VmBus client +will first attempt to use regular, non-isolated mechanisms for communication. +To do this, it must: + +* Configure the paravisor SIMP with an encrypted page. The paravisor SIMP is + configured by setting the relevant MSR directly, without using GHCB or tdcall. + +* Enable SINT 2 on both the paravisor and hypervisor, without setting the proxy + flag on the paravisor SINT. Enable interrupts on the paravisor SynIC. + +* Configure both the paravisor and hypervisor event flags page. + Both pages will need to be scanned when VmBus receives a channel interrupt. + +* Send messages to the paravisor by calling HvPostMessage directly, without using + GHCB or tdcall. + +* Set the EOM MSR directly in the paravisor, without using GHCB or tdcall. + +If sending the InitiateContact message using non-isolated HvPostMessage fails, +the client must fall back to using the hypervisor synic, by using the GHCB/tdcall +as appropriate. + +To fall back, the client will have to reconfigure the following: + +* Configure the hypervisor SIMP with a host-visible page. + Since the hypervisor SIMP is not used when in confidential mode, + this can be done up front, or only when needed, whichever makes sense for + the particular implementation. + +* Set the proxy flag on SINT 2 for the paravisor.
Define what the confidential VMBus is and describe what advantages it offers on the capable hardware. Signed-off-by: Roman Kisel <romank@linux.microsoft.com> --- Documentation/virt/hyperv/vmbus.rst | 41 +++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+)