mirror of https://github.com/xemu-project/xemu.git
84d4b72854
This bug fix addresses the incorrect return value of kvm_hv_handle_exit for
KVM_EXIT_HYPERV_SYNIC, which should be EXCP_INTERRUPT.
Handling of KVM_EXIT_HYPERV_SYNIC in QEMU needs to be synchronous.
This means that async_synic_update should run in the current QEMU vCPU
thread before returning to KVM, returning EXCP_INTERRUPT to guarantee this.
Returning 0 can cause async_synic_update to run asynchronously.
One problem (kvm-unit-tests's hyperv_synic test fails with timeout error)
caused by this bug:
When a guest VM writes to the HV_X64_MSR_SCONTROL MSR to enable Hyper-V SynIC,
a VM exit is triggered and processed by the kvm_hv_handle_exit function of the
QEMU vCPU. This function then calls the async_synic_update function to set
synic->sctl_enabled to true. A true value of synic->sctl_enabled is required
before creating SINT routes using the hyperv_sint_route_new() function.
If kvm_hv_handle_exit returns 0 for KVM_EXIT_HYPERV_SYNIC, the current QEMU
vCPU thread may return to KVM and enter the guest VM before running
async_synic_update. In such case, the hyperv_synic test’s subsequent call to
synic_ctl(HV_TEST_DEV_SINT_ROUTE_CREATE, ...) immediately after writing to
HV_X64_MSR_SCONTROL can cause QEMU’s hyperv_sint_route_new() function to return
prematurely (because synic->sctl_enabled is false).
If the SINT route is not created successfully, the SINT interrupt will not be
fired, resulting in a timeout error in the hyperv_synic test.
Fixes:
|
||
|---|---|---|
| .. | ||
| alpha | ||
| arm | ||
| avr | ||
| cris | ||
| hexagon | ||
| hppa | ||
| i386 | ||
| loongarch | ||
| m68k | ||
| microblaze | ||
| mips | ||
| openrisc | ||
| ppc | ||
| riscv | ||
| rx | ||
| s390x | ||
| sh4 | ||
| sparc | ||
| tricore | ||
| xtensa | ||
| Kconfig | ||
| meson.build | ||