[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] libacpi: fix PCI hotplug AML
commit b190af7d3e90f58da5f58044b8dea7261b8b483d Author: David Woodhouse <dwmw@xxxxxxxxxxxx> AuthorDate: Mon Mar 20 17:12:34 2023 +0100 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Mon Mar 20 17:12:34 2023 +0100 libacpi: fix PCI hotplug AML The emulated PIIX3 uses a nybble for the status of each PCI function, so the status for e.g. slot 0 functions 0 and 1 respectively can be read as (\_GPE.PH00 & 0x0F), and (\_GPE.PH00 >> 0x04). The AML that Xen gives to a guest gets the operand order for the odd- numbered functions the wrong way round, returning (0x04 >> \_GPE.PH00) instead. As far as I can tell, this was the wrong way round in Xen from the moment that PCI hotplug was first introduced in commit 83d82e6f35a8: + ShiftRight (0x4, \_GPE.PH00, Local1) + Return (Local1) /* IN status as the _STA */ Or maybe there's bizarre AML operand ordering going on there, like Intel's wrong-way-round assembler, and it only broke later when it was changed to being generated? Either way, it's definitely wrong now, and instrumenting a Linux guest shows that it correctly sees _STA being 0x00 in function 0 of an empty slot, but then the loop in acpiphp_glue.c::get_slot_status() goes on to look at function 1 and sees that _STA evaluates to 0x04. Thus reporting an adapter is present in every slot in /sys/bus/pci/slots/* Quite why Linux wants to look for function 1 being physically present when function 0 isn't... I don't want to think about right now. Fixes: 83d82e6f35a8 ("hvmloader: pass-through: multi-function PCI hot-plug") Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> --- tools/libacpi/mk_dsdt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/libacpi/mk_dsdt.c b/tools/libacpi/mk_dsdt.c index 1176da80ef..1d27809116 100644 --- a/tools/libacpi/mk_dsdt.c +++ b/tools/libacpi/mk_dsdt.c @@ -431,7 +431,7 @@ int main(int argc, char **argv) stmt("Store", "0x89, \\_GPE.DPT2"); } if ( slot & 1 ) - stmt("ShiftRight", "0x4, \\_GPE.PH%02X, Local1", slot & ~1); + stmt("ShiftRight", "\\_GPE.PH%02X, 0x04, Local1", slot & ~1); else stmt("And", "\\_GPE.PH%02X, 0x0f, Local1", slot & ~1); stmt("Return", "Local1"); /* IN status as the _STA */ -- generated by git-patchbot for /home/xen/git/xen.git#master
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |