On 12/14/20 10:45 AM, 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?
>
Or maybe @len in case you want to consider @gpa = 0 as valid.
>> + 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 {
>>
