On 5/2/19 2:52 AM, Tamas K Lengyel wrote:
> Currently the gs_shadow value is only cached when the vCPU is being scheduled
> out by Xen. Reporting this (usually) stale value through vm_event is
> incorrect,
> since it doesn't represent the actual state of the vCPU at the time the event
> was recorded. This prevents vm_event subscribers from correctly finding kernel
> structures in the guest when it is trapped while in ring3.
>
> Refresh shadow_gs value when the context being saved is for the current vCPU.
>
> Signed-off-by: Tamas K Lengyel <ta...@tklengyel.com>
> Cc: Razvan Cojocaru <rcojoc...@bitdefender.com>
> Cc: Jun Nakajima <jun.nakaj...@intel.com>
> Cc: Kevin Tian <kevin.t...@intel.com>
> Cc: Jan Beulich <jbeul...@suse.com>
> Cc: Andrew Cooper <andrew.coop...@citrix.com>
> Cc: Wei Liu <wei.l...@citrix.com>
> Cc: Roger Pau Monne <roger....@citrix.com>
> ---
> v2: move fix to hvm so vm_event doesn't have to know specifics
> ---
> xen/arch/x86/hvm/vmx/vmx.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> index 283eb7b34d..5154ecc2a8 100644
> --- a/xen/arch/x86/hvm/vmx/vmx.c
> +++ b/xen/arch/x86/hvm/vmx/vmx.c
> @@ -779,12 +779,17 @@ static void vmx_load_cpu_state(struct vcpu *v, struct
> hvm_hw_cpu *data)
>
> static void vmx_save_vmcs_ctxt(struct vcpu *v, struct hvm_hw_cpu *ctxt)
> {
> + if ( v == current )
> + vmx_save_guest_msrs(v);
vmx_save_guest_msrs() is simple enough that the if is probably not
necessary here (we can just call the function directly, regardless of
what v holds).
But that's not technically an issue, so if nobody else minds:
Acked-by: Razvan Cojocaru <rcojoc...@bitdefender.com>
Thanks,
Razvan
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