Messages in this thread | | | Subject | Re: [PATCH v3] KVM: X86: Fix load RFLAGS w/o the fixed bit | From | Quan Xu <> | Date | Thu, 7 Dec 2017 17:24:28 +0800 |
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On 2017/12/07 16:30, Wanpeng Li wrote: > 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> > Reviewed-by: David Hildenbrand <david@redhat.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> Reviewed-by: Quan Xu <quan.xu0@gmail.com>
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