On Tue, May 20, 2025 at 01:30:07PM +0200, Magnus Kulke wrote:
> Implement MSHV-specific hooks for vCPU creation and teardown in the
> i386 target. A list of locks per vCPU is maintained to lock CPU state in
> MMIO operations.
>
> Signed-off-by: Magnus Kulke <magnusku...@linux.microsoft.com>
> ---
> target/i386/mshv/mshv-cpu.c | 61 +++++++++++++++++++++++++++++++++----
> 1 file changed, 55 insertions(+), 6 deletions(-)
>
> diff --git a/target/i386/mshv/mshv-cpu.c b/target/i386/mshv/mshv-cpu.c
> index c4b2c297e2..0ba1dacaed 100644
> --- a/target/i386/mshv/mshv-cpu.c
> +++ b/target/i386/mshv/mshv-cpu.c
> @@ -14,6 +14,8 @@
> */
>
> #include "qemu/osdep.h"
> +#include "qemu/atomic.h"
> +#include "qemu/lockable.h"
> #include "qemu/error-report.h"
> #include "qemu/typedefs.h"
>
> @@ -30,6 +32,36 @@
> #include "trace-accel_mshv.h"
> #include "trace.h"
>
> +#include <sys/ioctl.h>
> +
> +static QemuMutex *cpu_guards_lock;
> +static GHashTable *cpu_guards;
> +
> +static void add_cpu_guard(int cpu_fd)
> +{
> + QemuMutex *guard;
> +
> + WITH_QEMU_LOCK_GUARD(cpu_guards_lock) {
> + guard = g_new0(QemuMutex, 1);
> + qemu_mutex_init(guard);
> + g_hash_table_insert(cpu_guards, GUINT_TO_POINTER(cpu_fd), guard);
> + }
> +}
> +
> +static void remove_cpu_guard(int cpu_fd)
> +{
> + QemuMutex *guard;
> +
> + WITH_QEMU_LOCK_GUARD(cpu_guards_lock) {
> + guard = g_hash_table_lookup(cpu_guards, GUINT_TO_POINTER(cpu_fd));
> + if (guard) {
> + qemu_mutex_destroy(guard);
> + g_free(guard);
> + g_hash_table_remove(cpu_guards, GUINT_TO_POINTER(cpu_fd));
> + }
> + }
> +}
> +
> int mshv_store_regs(CPUState *cpu)
> {
> error_report("unimplemented");
> @@ -62,20 +94,37 @@ int mshv_run_vcpu(int vm_fd, CPUState *cpu, hv_message
> *msg, MshvVmExit *exit)
>
> void mshv_remove_vcpu(int vm_fd, int cpu_fd)
> {
> - error_report("unimplemented");
> - abort();
> + /*
> + * TODO: don't we have to perform an ioctl to remove the vcpu?
> + * there is WHvDeleteVirtualProcessor in the WHV api
> + */
> + remove_cpu_guard(cpu_fd);
Can you just park that CPU and never schedule it again?
There is a DELETE_VP call but we may not have exposed that to user
space.
The code as-is seems to be leaking the cpu_fd. If it is handled
elsewhere you can ignore this comment.
Thanks,
Wei.
> }
>
> +
> int mshv_create_vcpu(int vm_fd, uint8_t vp_index, int *cpu_fd)
> {
> - error_report("unimplemented");
> - abort();
> + int ret;
> + struct mshv_create_vp vp_arg = {
> + .vp_index = vp_index,
> + };
> + ret = ioctl(vm_fd, MSHV_CREATE_VP, &vp_arg);
> + if (ret < 0) {
> + error_report("failed to create mshv vcpu: %s", strerror(errno));
> + return -1;
> + }
> +
> + add_cpu_guard(ret);
> + *cpu_fd = ret;
> +
> + return 0;
> }
>
> void mshv_init_cpu_logic(void)
> {
> - error_report("unimplemented");
> - abort();
> + cpu_guards_lock = g_new0(QemuMutex, 1);
> + qemu_mutex_init(cpu_guards_lock);
> + cpu_guards = g_hash_table_new(g_direct_hash, g_direct_equal);
> }
>
> void mshv_arch_init_vcpu(CPUState *cpu)
> --
> 2.34.1
>
