On 05/28/2015 07:31 AM, Daniel P. Berrange wrote:
On Thu, May 21, 2015 at 07:03:28PM -0400, Cole Robinson wrote:
We need to use qemu-system-aarch64 to run armv7l KVM VMs on an aarch64 host. --- src/qemu/qemu_capabilities.c | 42 ++++++++++++++++++++++-------------------- 1 file changed, 22 insertions(+), 20 deletions(-)
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index 1e7bddb..7181865 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -723,19 +723,6 @@ virQEMUCapsFindBinaryForArch(virArch hostarch, return ret; }
- -static bool -virQEMUCapsIsValidForKVM(virArch hostarch, - virArch guestarch) -{ - if (hostarch == guestarch) - return true; - if (hostarch == VIR_ARCH_X86_64 && - guestarch == VIR_ARCH_I686) - return true; - return false; -} - static int virQEMUCapsInitGuest(virCapsPtr caps, virQEMUCapsCachePtr cache, @@ -747,6 +734,7 @@ virQEMUCapsInitGuest(virCapsPtr caps, char *binary = NULL; virQEMUCapsPtr qemubinCaps = NULL; virQEMUCapsPtr kvmbinCaps = NULL; + bool native_kvm, x86_32on64_kvm, arm_32on64_kvm; int ret = -1;
/* Check for existence of base emulator, or alternate base @@ -764,16 +752,30 @@ virQEMUCapsInitGuest(virCapsPtr caps,
/* qemu-kvm/kvm binaries can only be used if * - host & guest arches match - * Or - * - hostarch is x86_64 and guest arch is i686 - * The latter simply needs "-cpu qemu32" + * - hostarch is x86_64 and guest arch is i686 (needs -cpu qemu32) + * - hostarch is aarch64 and guest arch is armv7l (needs -cpu aarch64=off) */ - if (virQEMUCapsIsValidForKVM(hostarch, guestarch)) { - const char *const kvmbins[] = { "/usr/libexec/qemu-kvm", /* RHEL */ - "qemu-kvm", /* Fedora */ - "kvm" }; /* Upstream .spec */ + native_kvm = (hostarch == guestarch); + x86_32on64_kvm = (hostarch == VIR_ARCH_X86_64 && + guestarch == VIR_ARCH_I686); + arm_32on64_kvm = (hostarch == VIR_ARCH_AARCH64 && + guestarch == VIR_ARCH_ARMV7L); + + if (native_kvm || x86_32on64_kvm || arm_32on64_kvm) { + const char *kvmbins[] = { + "/usr/libexec/qemu-kvm", /* RHEL */ + "qemu-kvm", /* Fedora */ + "kvm", /* Debian/Ubuntu */ + NULL, + }; + + if (arm_32on64_kvm) + kvmbins[3] = "qemu-system-aarch64";
I'm unclear why you need to be adding this. We don't need it for the equivalent i686 with qemu-system-x86_64, as the earlier call to virQEMUCapsFindBinaryForArch() will already return the binary qemu-system-x86_64. IIUC, it should have returned the binary qemu-system-aarch64 too, so this just seems to duplicate the check for that binary.
We need this in the case you are running on an aarch64 host and have both qemu-system-arm and qemu-system-aarch64 installed. In this case, when you want to use KVM for arm32, you _have_ to use qemu-system-aarch64, qemu-system-arm does not work. What you suggest would mean that qemu-system-arm is grabbed from the caps cache. x86 doesn't have this problem because qemu-system-i386, qemu-system-x86_64 and by extension qemu-kvm can all be used to do 32-on-64 KVM. Thanks, Cole