[PATCH v16 18/20] KVM: selftests: Add support for per-VM ucall ops on x86

[Lisa Wang <wyihan@google.com>]

From: Sean Christopherson <seanjc@google.com>

Add a layer of indirection to x86's ucall infrastructure to allow wiring up
a different set of {do,get}_ucall() operations for TDX VMs.  TDX can't use
port I/O (at least, not robustly), as the TDX ABI doesn't allow the guest
to share arbitrary register state with the host on a PIO exit, and the PIO
data payload is limited to 4 bytes, i.e. would potentially truncate the
address of the per-ucall structure.

No functional change intended, as the ops are still hardwired to the common
x86 ucall functions.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Lisa Wang <wyihan@google.com>
---
 tools/testing/selftests/kvm/include/x86/ucall.h |  6 +-----
 tools/testing/selftests/kvm/lib/x86/ucall.c     | 27 +++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/x86/ucall.h b/tools/testing/selftests/kvm/include/x86/ucall.h
index 0e4950041e3e..aca582bb2cd5 100644
--- a/tools/testing/selftests/kvm/include/x86/ucall.h
+++ b/tools/testing/selftests/kvm/include/x86/ucall.h
@@ -2,12 +2,8 @@
 #ifndef SELFTEST_KVM_UCALL_H
 #define SELFTEST_KVM_UCALL_H
 
-#include "kvm_util.h"
+#include <linux/kvm.h>
 
 #define UCALL_EXIT_REASON       KVM_EXIT_IO
 
-static inline void ucall_arch_init(struct kvm_vm *vm, gpa_t mmio_gpa)
-{
-}
-
 #endif
diff --git a/tools/testing/selftests/kvm/lib/x86/ucall.c b/tools/testing/selftests/kvm/lib/x86/ucall.c
index 38050c60a067..3aec4dd46d1b 100644
--- a/tools/testing/selftests/kvm/lib/x86/ucall.c
+++ b/tools/testing/selftests/kvm/lib/x86/ucall.c
@@ -8,13 +8,13 @@
 
 #define UCALL_PIO_PORT ((u16)0x1000)
 
-void ucall_arch_do_ucall(gva_t uc)
+static void ucall_x86_do_ucall(gva_t uc)
 {
 	asm volatile("in %[port], %%al"
 		: : [port] "d" (UCALL_PIO_PORT), "D" (uc) : "rax", "memory");
 }
 
-void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
+static void *ucall_x86_get_ucall(struct kvm_vcpu *vcpu)
 {
 	struct kvm_run *run = vcpu->run;
 
@@ -26,3 +26,26 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
 	}
 	return NULL;
 }
+
+static struct {
+	void (*do_ucall)(gva_t uc);
+	void *(*get_ucall)(struct kvm_vcpu *vcpu);
+} ucall_x86_ops = {
+	.do_ucall = ucall_x86_do_ucall,
+	.get_ucall = ucall_x86_get_ucall,
+};
+
+void ucall_arch_init(struct kvm_vm *vm, gpa_t mmio_gpa)
+{
+	sync_global_to_guest(vm, ucall_x86_ops);
+}
+
+void ucall_arch_do_ucall(gva_t uc)
+{
+	ucall_x86_ops.do_ucall(uc);
+}
+
+void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
+{
+	return ucall_x86_ops.get_ucall(vcpu);
+}

-- 
2.56.0.455.g6c5a503b38-goog