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?
> + return 0;
> +}
And then here you just return @ret while removing the other conditional.
> +
> int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
> {
> int r = -ENOENT;
> @@ -28,6 +42,11 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
> kvm->arch.xen.long_mode = !!data->u.long_mode;
> r = 0;
> break;
> +
> + case KVM_XEN_ATTR_TYPE_SHARED_INFO:
> + r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);
> + break;
> +
> default:
> break;
> }
> @@ -44,6 +63,14 @@ int kvm_xen_hvm_get_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
> data->u.long_mode = kvm->arch.xen.long_mode;
> r = 0;
> break;
> +
> + case KVM_XEN_ATTR_TYPE_SHARED_INFO:
> + if (kvm->arch.xen.shinfo_set) {
> + data->u.shared_info.gfn = gpa_to_gfn(kvm->arch.xen.shinfo_cache.gpa);
> + r = 0;
> + }
> + break;
> +
> default:
> break;
> }
> diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
> index cd3c52b62068..120b7450252a 100644
> --- 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 ?
> static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)
> {
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 6b556ef98b76..caa9faf3c5ad 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1585,11 +1585,15 @@ struct kvm_xen_hvm_attr {
>
> union {
> __u8 long_mode;
> + struct {
> + __u64 gfn;
> + } shared_info;
> __u64 pad[4];
> } u;
> };
>
> #define KVM_XEN_ATTR_TYPE_LONG_MODE 0x0
> +#define KVM_XEN_ATTR_TYPE_SHARED_INFO 0x1
>
> /* Secure Encrypted Virtualization command */
> enum sev_cmd_id {
>
