2017-10-09 15:51-0700, Wanpeng Li:
> From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>
> - XCR0 is reset to 1 by RESET but not INIT
> - XSS is zeroed by both RESET and INIT
> - BNDCFGU, BND0-BND3, BNDCFGS are zeroed by both RESET and INIT
>
> This patch does this according to SDM.
>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
> Cc: Jim Mattson <jmattson@xxxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
> ---
> v2 -> v3:
> * fix null pointer deference
> * fix patch description
> v1 -> v2:
> * XCR0 is not zeroed by INIT
> * XSS, BNDCFGU, BND0-BND3, BNDCFGS are zeroed by both RESET and INIT
>
> arch/x86/kvm/vmx.c | 2 ++
> arch/x86/kvm/x86.c | 15 +++++++++++++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> @@ -7804,18 +7804,33 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> kvm_async_pf_hash_reset(vcpu);
> vcpu->arch.apf.halted = false;
>
> + if (kvm_mpx_supported()) {
> + void *mpx_state_buffer;
> +
> + mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu.state.xsave, XFEATURE_MASK_BNDREGS);
> + if (mpx_state_buffer)
> + memset(mpx_state_buffer, 0, sizeof(struct mpx_bndreg_state));
I think we should call kvm_put_guest_fpu() before doing this.
The register might be loaded in CPU and XSAVE instruction from
vcpu_put() would overwrite any changes we did.
> + mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu.state.xsave, XFEATURE_MASK_BNDCSR);
> + if (mpx_state_buffer)
> + memset(mpx_state_buffer, 0, sizeof(u64));
XFEATURE_MASK_BNDCSR is actually
struct mpx_bndcsr {
u64 bndcfgu;
u64 bndstatus;
} __packed;
So clearing two u64 would be correct, thanks.
