Messages in this thread Patch in this message | | | From | Wanpeng Li <> | Subject | [PATCH v2] KVM: X86: Fix load RFLAGS w/o the fixed bit | Date | Wed, 6 Dec 2017 03:59:18 -0800 |
| |
From: Wanpeng Li <wanpeng.li@hotmail.com>
*** Guest State *** CR0: actual=0x0000000000000030, shadow=0x0000000060000010, gh_mask=fffffffffffffff7 CR4: actual=0x0000000000002050, shadow=0x0000000000000000, gh_mask=ffffffffffffe871 CR3 = 0x00000000fffbc000 RSP = 0x0000000000000000 RIP = 0x0000000000000000 RFLAGS=0x00000000 DR7 = 0x0000000000000400 ^^^^^^^^^^
The failed vmentry is triggered by the following testcase when ept=Y:
#include <unistd.h> #include <sys/syscall.h> #include <string.h> #include <stdint.h> #include <linux/kvm.h> #include <fcntl.h> #include <sys/ioctl.h> long r[5]; int main() { r[2] = open("/dev/kvm", O_RDONLY); r[3] = ioctl(r[2], KVM_CREATE_VM, 0); r[4] = ioctl(r[3], KVM_CREATE_VCPU, 7); struct kvm_regs regs = { .rflags = 0, }; ioctl(r[4], KVM_SET_REGS, ®s); ioctl(r[4], KVM_RUN, 0); }
X86 RFLAGS bit 1 is fixed set, userspace can simply clearing bit 1 of RFLAGS with KVM_SET_REGS ioctl which results in vmentry fails. This patch fixes it by oring X86_EFLAGS_FIXED during ioctl.
Suggested-by: Jim Mattson <jmattson@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Jim Mattson <jmattson@google.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> --- v1 -> v2: * Oring X86_EFLAGS_FIXED
virt/kvm/kvm_main.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b55bad3..0f3f283 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2602,6 +2602,7 @@ static long kvm_vcpu_ioctl(struct file *filp, r = PTR_ERR(kvm_regs); goto out; } + kvm_regs->rflags |= X86_EFLAGS_FIXED; r = kvm_arch_vcpu_ioctl_set_regs(vcpu, kvm_regs); kfree(kvm_regs); break; -- 2.7.4
| |