[PATCH 07/19] kvm: x86: Propagate fpstate reallocation error to userspace

Yang Zhong
2021-12-07T15:09:40Z

From: Jing Liu <jing2.liu@intel.com>

fpstate reallocation is handled when the vCPU thread returns
to userspace. As reallocation could fail (e.g. lack of memory),
this patch extends kvm_put_guest_fpu() to return an integer value
to carry error code to userspace VMM. The userspace VMM is expected
to handle any error caused by fpstate reallocation.

Signed-off-by: Jing Liu <jing2.liu@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
arch/x86/kvm/x86.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0ee1a039b490..05f2cda73d69 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10171,17 +10171,21 @@ static void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
}

/* When vcpu_run ends, restore user space FPU context. */
-static void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
+static int kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
{
- fpu_swap_kvm_fpstate(&vcpu->arch.guest_fpu, false);
+ int ret;
+
+ ret = fpu_swap_kvm_fpstate(&vcpu->arch.guest_fpu, false);
++vcpu->stat.fpu_reload;
trace_kvm_fpu(0);
+
+ return ret;
}

int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
{
struct kvm_run *kvm_run = vcpu->run;
- int r;
+ int r, ret;

vcpu_load(vcpu);
kvm_sigset_activate(vcpu);
@@ -10243,7 +10247,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
r = vcpu_run(vcpu);

out:
- kvm_put_guest_fpu(vcpu);
+ ret = kvm_put_guest_fpu(vcpu);
+ if ((r >= 0) && (ret < 0))
+ r = ret;
+
if (kvm_run->kvm_valid_regs)
store_regs(vcpu);
post_kvm_run_save(vcpu);