From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
TDX requires vMMIO region to be shared. For KVM, MMIO region is the region
which kvm memslot isn't assigned to (except in-kernel emulation).
qemu has the memory region for vMMIO at each device level.
While OVMF issues MapGPA(to-shared) conservatively on 32bit PCI MMIO
region, qemu doesn't find corresponding vMMIO region because it's before
PCI device allocation and memory_region_find() finds the device region, not
PCI bus region. It's safe to ignore MapGPA(to-shared) because when guest
accesses those region they use GPA with shared bit set for vMMIO. Ignore
memory conversion request of non-assigned region to shared and return
success. Otherwise OVMF is confused and panics there.
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
accel/kvm/kvm-all.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 9d0aa8c97feb..8d53c89e9dbf 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -3070,6 +3070,18 @@ static int kvm_convert_memory(hwaddr start, hwaddr size, bool to_private)
trace_kvm_convert_memory(start, size, to_private ? "shared_to_private" : "private_to_shared");
section = memory_region_find(get_system_memory(), start, size);
if (!section.mr) {
+ /*
+ * Ignore converting non-assigned region to shared.
+ *
+ * TDX requires vMMIO region to be shared to inject #VE to guest.
+ * OVMF issues conservatively MapGPA(shared) on 32bit PCI MMIO region,
+ * and vIO-APIC 0xFEC00000 4K page.
+ * OVMF assigns 32bit PCI MMIO region to
+ * [top of low memory: typically 2GB=0xC000000, 0xFC00000)
+ */
+ if (!to_private) {
+ ret = 0;
+ }
return ret;
}
--
2.34.1
