diff options
Diffstat (limited to '0046-libacpi-fix-PCI-hotplug-AML.patch')
| -rw-r--r-- | 0046-libacpi-fix-PCI-hotplug-AML.patch | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/0046-libacpi-fix-PCI-hotplug-AML.patch b/0046-libacpi-fix-PCI-hotplug-AML.patch new file mode 100644 index 0000000..b1c79f5 --- /dev/null +++ b/0046-libacpi-fix-PCI-hotplug-AML.patch @@ -0,0 +1,57 @@ +From 54102e428ba3f677904278479f8110c8eef6fedc Mon Sep 17 00:00:00 2001 +From: David Woodhouse <dwmw@amazon.co.uk> +Date: Tue, 21 Mar 2023 13:53:25 +0100 +Subject: [PATCH 46/61] 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@amazon.co.uk> +Reviewed-by: Jan Beulich <jbeulich@suse.com> +master commit: b190af7d3e90f58da5f58044b8dea7261b8b483d +master date: 2023-03-20 17:12:34 +0100 +--- + 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 c5ba4c0b2f..250a50b7eb 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 */ +-- +2.40.0 + |