Re: [Xen-devel] [PATCH RFC 6/9] xen, libxc: Request page fault injection via libxc

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.07.14 at 15:33, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> Added new XEN_DOMCTL_set_pagefault_info hypercall, used by libxc's
> new xc_domain_set_pagefault_info() function to set per-domain page
> fault injection information. This information is then used to call
> hvm_inject_page_fault() at the first VMENTRY where the guest status
> matches and there are no other pending traps.

So the first question that strikes me here: What good can it do to be
able to inject arbitrary page faults, possibly at times where the guest
OS is absolutely not expecting them?

> @@ -430,6 +431,9 @@ static void vmx_vmcs_save(struct vcpu *v, struct 
> hvm_hw_cpu *c)
>      __vmread(GUEST_SYSENTER_CS, &c->sysenter_cs);
>      __vmread(GUEST_SYSENTER_ESP, &c->sysenter_esp);
>      __vmread(GUEST_SYSENTER_EIP, &c->sysenter_eip);
> +    __vmread(GUEST_CS_AR_BYTES, &cs_arbytes);
> +
> +    c->cs_arbytes = (uint32_t)cs_arbytes;

This again looks like an unrelated change without any explanation.

Jan


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