On 31/01/2019 08:19, Christoffer Dall wrote:
On Mon, Jan 28, 2019 at 03:42:42PM +0000, Julien Thierry wrote:
Hi James,
On 28/01/2019 11:48, James Morse wrote:
Hi Julien,
On 21/01/2019 15:33, Julien Thierry wrote:
When using VHE, the host needs to clear HCR_EL2.TGE bit in order to interract with guest TLBs, switching from EL2&0 translation regime
(interact)
to EL1&0.
However, some non-maskable asynchronous event could happen while TGE is cleared like SDEI. Because of this address translation operations relying on EL2&0 translation regime could fail (tlb invalidation, userspace access, ...).
Fix this by properly setting HCR_EL2.TGE when entering NMI context and clear it if necessary when returning to the interrupted context.
Yes please. This would not have been fun to debug!
Reviewed-by: James Morse james.morse@arm.com
Thanks.
I was looking for why we need core code to do this, instead of updating the arch's call sites. Your 'irqdesc: Add domain handlers for NMIs' patch (pointed to from the cover letter) is the reason: core-code calls nmi_enter()/nmi_exit() itself.
Yes, that's the main reason.
I wondered the same thing, but I don't understand the explanation :(
Why can't we do a local_daif_mask() around the (very small) calls that clear TGE instead?
That would protect against the pseudo-NMIs, but you can still get an SDEI at that point even with all daif bits set. Or did I misunderstand how SDEI works?
Thanks,