On Mon, 2020-12-14 at 10:45 +0000, Joao Martins wrote:
> On 12/14/20 8:38 AM, David Woodhouse wrote:
> > From: Joao Martins <joao.m.martins@xxxxxxxxxx>
> >
> > We add a new ioctl, XEN_HVM_SHARED_INFO, to allow hypervisor
> > to know where the guest's shared info page is.
> >
> > Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
> > Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> > ---
> > arch/x86/include/asm/kvm_host.h | 2 ++
> > arch/x86/kvm/xen.c | 27 +++++++++++++++++++++++++++
> > arch/x86/kvm/xen.h | 1 -
> > include/uapi/linux/kvm.h | 4 ++++
> > 4 files changed, 33 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/include/asm/kvm_host.h
> > b/arch/x86/include/asm/kvm_host.h
> > index c9a4feaee2e7..8bcd83dacf43 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -893,6 +893,8 @@ struct msr_bitmap_range {
> > /* Xen emulation context */
> > struct kvm_xen {
> > bool long_mode;
> > + bool shinfo_set;
> > + struct gfn_to_hva_cache shinfo_cache;
> > };
> >
> > enum kvm_irqchip_mode {
> > diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
> > index 52cb9e465542..9dd9c42842b8 100644
> > --- a/arch/x86/kvm/xen.c
> > +++ b/arch/x86/kvm/xen.c
> > @@ -13,9 +13,23 @@
> > #include <linux/kvm_host.h>
> >
> > #include <trace/events/kvm.h>
> > +#include <xen/interface/xen.h>
> >
> > #include "trace.h"
> >
> > +static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
> > +{
> > + int ret;
> > +
> > + ret = kvm_gfn_to_hva_cache_init(kvm, &kvm-
> > >arch.xen.shinfo_cache,
> > + gfn_to_gpa(gfn), PAGE_SIZE);
> > + if (ret)
> > + return ret;
> > +
> > + kvm->arch.xen.shinfo_set = true;
>
> Can't you just use:
>
> kvm->arch.xen.shinfo_cache.gpa
>
> Rather than added a bool just to say you set a shinfo?
I see no reason why a guest shouldn't be able to use GPA zero if it
really wanted to. Using a separate boolean matches what KVM does for
the wallclock info.
> > --- a/arch/x86/kvm/xen.h
> > +++ b/arch/x86/kvm/xen.h
> > @@ -13,7 +13,6 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct
> > kvm_xen_hvm_attr *data);
> > int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr
> > *data);
> > int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
> > int kvm_xen_hvm_config(struct kvm_vcpu *vcpu, u64 data);
> > -void kvm_xen_destroy_vm(struct kvm *kvm);
> >
>
> spurious deletion ?
Now nothing is kept mapped, there's no need for a destroy function. It
must have been spuriously *added* in a previous patch and then deleted
here. Will fix.
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