[PATCH 06/18] KVM: x86: hyper-v: Exit on Get/SetVpRegisters hcall

Nicolas Saenz Julienne
2024-06-09T15:54:40Z

Let user-space handle HvGetVpRegisters and HvSetVpRegisters as they are
VTL aware hypercalls used solely in the context of VSM. Additionally,
expose the cpuid bit.

Signed-off-by: Nicolas Saenz Julienne <nsaenz@amazon.com>
---
Documentation/virt/kvm/api.rst | 10 ++++++++++
arch/x86/kvm/hyperv.c | 15 +++++++++++++++
include/asm-generic/hyperv-tlfs.h | 1 +
3 files changed, 26 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index e664c54a13b04..05b01b00a395c 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8931,3 +8931,13 @@ CPUIDs map to KVM functionality.
This CPUID indicates that KVM supports retuning data to the guest in response
to a hypercall using the XMM registers. It also extends ``struct
kvm_hyperv_exit`` to allow passing the XMM data from userspace.
+
+10.2 HV_ACCESS_VP_REGISTERS
+---------------------------
+
+:Location: CPUID.40000003H:EBX[bit 17]
+
+This CPUID indicates that KVM supports HvGetVpRegisters and HvSetVpRegisters.
+Currently, it is only used in conjunction with HV_ACCESS_VSM, and immediately
+exits to userspace with KVM_EXIT_HYPERV_HCALL as the reason. Userspace is
+expected to complete the hypercall before resuming execution.
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index d00baf3ffb165..d0edc2bec5a4f 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -2425,6 +2425,11 @@ static void kvm_hv_write_xmm(struct kvm_hyperv_xmm_reg *xmm)

static bool kvm_hv_is_xmm_output_hcall(u16 code)
{
+ switch (code) {
+ case HVCALL_GET_VP_REGISTERS:
+ return true;
+ }
+
return false;
}

@@ -2505,6 +2510,8 @@ static bool is_xmm_fast_hypercall(struct kvm_hv_hcall *hc)
case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
case HVCALL_SEND_IPI_EX:
+ case HVCALL_GET_VP_REGISTERS:
+ case HVCALL_SET_VP_REGISTERS:
return true;
}

@@ -2543,6 +2550,10 @@ static bool hv_check_hypercall_access(struct kvm_vcpu_hv *hv_vcpu, u16 code)
*/
return !kvm_hv_is_syndbg_enabled(hv_vcpu->vcpu) ||
hv_vcpu->cpuid_cache.features_ebx & HV_DEBUGGING;
+ case HVCALL_GET_VP_REGISTERS:
+ case HVCALL_SET_VP_REGISTERS:
+ return hv_vcpu->cpuid_cache.features_ebx &
+ HV_ACCESS_VP_REGISTERS;
case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX:
case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX:
if (!(hv_vcpu->cpuid_cache.enlightenments_eax &
@@ -2727,6 +2738,9 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
break;
}
goto hypercall_userspace_exit;
+ case HVCALL_GET_VP_REGISTERS:
+ case HVCALL_SET_VP_REGISTERS:
+ goto hypercall_userspace_exit;
default:
ret = HV_STATUS_INVALID_HYPERCALL_CODE;
break;
@@ -2898,6 +2912,7 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
ent->ebx |= HV_POST_MESSAGES;
ent->ebx |= HV_SIGNAL_EVENTS;
ent->ebx |= HV_ENABLE_EXTENDED_HYPERCALLS;
+ ent->ebx |= HV_ACCESS_VP_REGISTERS;

ent->edx |= HV_X64_HYPERCALL_XMM_INPUT_AVAILABLE;
ent->edx |= HV_X64_HYPERCALL_XMM_OUTPUT_AVAILABLE;
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 28cde641b5474..9e909f0834598 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -90,6 +90,7 @@
#define HV_DEBUGGING BIT(11)
#define HV_CPU_MANAGEMENT BIT(12)
#define HV_ACCESS_VSM BIT(16)
+#define HV_ACCESS_VP_REGISTERS BIT(17)
#define HV_ENABLE_EXTENDED_HYPERCALLS BIT(20)
#define HV_ISOLATION BIT(22)

--
2.40.1