[6.6 regression] qemu-system-riscv64: Unable to read ISA_EXT KVM register ssaia, error -1

[Palmer Dabbelt]

On Thu, 09 Nov 2023 01:19:20 PST (-0800), schwab at suse.de wrote:
> v6.6 broke KVM with qemu 8.1.2.

Do you have known good commits for those?  It'd help for somone trying 
to bisect...

> $ qemu-system-riscv64 -cpu rv64 -machine virt,accel=kvm
> qemu-system-riscv64: Unable to read ISA_EXT KVM register ssaia, error -1

What's the host, just QEMU of the same version?

> openat(AT_FDCWD, "/dev/kvm", O_RDWR|O_CLOEXEC) = 9
> ioctl(9, _IOC(_IOC_NONE, 0xae, 0x1, 0), 0) = 10
> ioctl(10, _IOC(_IOC_NONE, 0xae, 0x41, 0), 0) = 11
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = 0
> ioctl(11, _IOC(_IOC_WRITE, 0xae, 0xab, 0x10), 0x7fffd101e3f8) = -1 ENOENT (No such file or directory)
> write(2, "qemu-system-riscv64:", 20qemu-system-riscv64:)    = 20
> write(2, " ", 1 )                        = 1
> write(2, "Unable to read ISA_EXT KVM regis"..., 51Unable to read ISA_EXT KVM register ssaia, error -1) = 51
> write(2, "\n", 1
> )                       = 1
> close(11)                               = 0
> close(10)                               = 0
> close(9)                                = 0
> exit_group(1)                           = ?
> +++ exited with 1 +++