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authorChristoffer Dall <christoffer.dall@linaro.org>2018-02-23 17:23:57 +0100
committerMarc Zyngier <marc.zyngier@arm.com>2018-05-25 12:27:54 +0100
commitbd2a6394fd2d3ea528d4b9c67f829e35f1f5d5dd (patch)
treee4e885532d9f66f769d421a98d0e2b11f12abb4a /virt/kvm/kvm_main.c
parent09d1223a62798846d223c25debeb55bf3d0d4905 (diff)
downloadlinux-bd2a6394fd2d3ea528d4b9c67f829e35f1f5d5dd.tar.gz
KVM: arm/arm64: Introduce kvm_arch_vcpu_run_pid_change
KVM/ARM differs from other architectures in having to maintain an additional virtual address space from that of the host and the guest, because we split the execution of KVM across both EL1 and EL2. This results in a need to explicitly map data structures into EL2 (hyp) which are accessed from the hyp code. As we are about to be more clever with our FPSIMD handling on arm64, which stores data in the task struct and uses thread_info flags, we will have to map parts of the currently executing task struct into the EL2 virtual address space. However, we don't want to do this on every KVM_RUN, because it is a fairly expensive operation to walk the page tables, and the common execution mode is to map a single thread to a VCPU. By introducing a hook that architectures can select with HAVE_KVM_VCPU_RUN_PID_CHANGE, we do not introduce overhead for other architectures, but have a simple way to only map the data we need when required for arm64. This patch introduces the framework only, and wires it up in the arm/arm64 KVM common code. No functional change. Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org> Signed-off-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'virt/kvm/kvm_main.c')
-rw-r--r--virt/kvm/kvm_main.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c7b2e927f699..c32e2407713d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2550,8 +2550,13 @@ static long kvm_vcpu_ioctl(struct file *filp,
oldpid = rcu_access_pointer(vcpu->pid);
if (unlikely(oldpid != current->pids[PIDTYPE_PID].pid)) {
/* The thread running this VCPU changed. */
- struct pid *newpid = get_task_pid(current, PIDTYPE_PID);
+ struct pid *newpid;
+ r = kvm_arch_vcpu_run_pid_change(vcpu);
+ if (r)
+ break;
+
+ newpid = get_task_pid(current, PIDTYPE_PID);
rcu_assign_pointer(vcpu->pid, newpid);
if (oldpid)
synchronize_rcu();