[PATCH v4 51/66] i386/tdx: handle TDG.VP.VMCALL<MapGPA> hypercall

[Xiaoyao Li <xiaoyao.li@xxxxxxxxx>]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

MapGPA is a hypercall to convert GPA from/to private GPA to/from shared GPA.
As the conversion function is already implemented as kvm_convert_memory,
wire it to TDX hypercall exit.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
 accel/kvm/kvm-all.c   |  2 +-
 include/sysemu/kvm.h  |  2 ++
 target/i386/kvm/tdx.c | 54 +++++++++++++++++++++++++++++++++++++++++++
 target/i386/kvm/tdx.h |  1 +
 4 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index eb8b3925dbe1..04309a8623d9 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2920,7 +2920,7 @@ static void kvm_eat_signals(CPUState *cpu)
     } while (sigismember(&chkset, SIG_IPI));
 }
 
-static int kvm_convert_memory(hwaddr start, hwaddr size, bool to_private)
+int kvm_convert_memory(hwaddr start, hwaddr size, bool to_private)
 {
     MemoryRegionSection section;
     ram_addr_t offset;
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index 2f6592859ac6..e0061848b053 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -544,4 +544,6 @@ int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp);
 
 int kvm_set_memory_attributes_private(hwaddr start, hwaddr size);
 int kvm_set_memory_attributes_shared(hwaddr start, hwaddr size);
+
+int kvm_convert_memory(hwaddr start, hwaddr size, bool to_private);
 #endif
diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c
index d27e775eec5d..f1c60274c448 100644
--- a/target/i386/kvm/tdx.c
+++ b/target/i386/kvm/tdx.c
@@ -884,6 +884,58 @@ static hwaddr tdx_shared_bit(X86CPU *cpu)
     return (cpu->phys_bits > 48) ? BIT_ULL(51) : BIT_ULL(47);
 }
 
+/* 64MB at most in one call. What value is appropriate? */
+#define TDX_MAP_GPA_MAX_LEN     (64 * 1024 * 1024)
+
+static int tdx_handle_map_gpa(X86CPU *cpu, struct kvm_tdx_vmcall *vmcall)
+{
+    hwaddr shared_bit = tdx_shared_bit(cpu);
+    hwaddr gpa = vmcall->in_r12 & ~shared_bit;
+    bool private = !(vmcall->in_r12 & shared_bit);
+    hwaddr size = vmcall->in_r13;
+    bool retry = false;
+    int ret = 0;
+
+    vmcall->status_code = TDG_VP_VMCALL_INVALID_OPERAND;
+
+    if (!QEMU_IS_ALIGNED(gpa, 4096) || !QEMU_IS_ALIGNED(size, 4096)) {
+        vmcall->status_code = TDG_VP_VMCALL_ALIGN_ERROR;
+        return 0;
+    }
+
+    /* Overflow case. */
+    if (gpa + size < gpa) {
+        return 0;
+    }
+    if (gpa >= (1ULL << cpu->phys_bits) ||
+        gpa + size >= (1ULL << cpu->phys_bits)) {
+        return 0;
+    }
+
+    if (size > TDX_MAP_GPA_MAX_LEN) {
+        retry = true;
+        size = TDX_MAP_GPA_MAX_LEN;
+    }
+
+    if (size > 0) {
+        ret = kvm_convert_memory(gpa, size, private);
+    }
+
+    if (!ret) {
+        if (retry) {
+            vmcall->status_code = TDG_VP_VMCALL_RETRY;
+            vmcall->out_r11 = gpa + size;
+            if (!private) {
+                vmcall->out_r11 |= shared_bit;
+            }
+        } else {
+            vmcall->status_code = TDG_VP_VMCALL_SUCCESS;
+        }
+    }
+
+    return 0;
+}
+
 static void tdx_get_quote_completion(struct tdx_generate_quote_task *task)
 {
     int ret;
@@ -1056,6 +1108,8 @@ static int tdx_handle_vmcall(X86CPU *cpu, struct kvm_tdx_vmcall *vmcall)
     }
 
     switch (vmcall->subfunction) {
+    case TDG_VP_VMCALL_MAP_GPA:
+        return tdx_handle_map_gpa(cpu, vmcall);
     case TDG_VP_VMCALL_GET_QUOTE:
         return tdx_handle_get_quote(cpu, vmcall);
     case TDG_VP_VMCALL_SETUP_EVENT_NOTIFY_INTERRUPT:
diff --git a/target/i386/kvm/tdx.h b/target/i386/kvm/tdx.h
index c6e4c275262d..cedc7d7e226f 100644
--- a/target/i386/kvm/tdx.h
+++ b/target/i386/kvm/tdx.h
@@ -18,6 +18,7 @@ typedef struct TdxGuestClass {
     ConfidentialGuestSupportClass parent_class;
 } TdxGuestClass;
 
+#define TDG_VP_VMCALL_MAP_GPA                           0x10001ULL
 #define TDG_VP_VMCALL_GET_QUOTE                         0x10002ULL
 #define TDG_VP_VMCALL_SETUP_EVENT_NOTIFY_INTERRUPT      0x10004ULL
 
-- 
2.34.1