From 7339bfeffa3fa30b18dce86409c0112039bacec5 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Wed, 29 May 2024 17:28:11 +0200
Subject: [PATCH] OvmfPkg/VirtioRngDxe: check if device is ready

Add a 'Ready' boolean to the driver state struct, use it to track
whenever the device is ready to be used.  In case it is not ready
throw an EFI_DEVICE_ERROR instead of sending a request which will
never receive an answer.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 OvmfPkg/VirtioRngDxe/VirtioRng.c | 13 ++++++++++---
 OvmfPkg/VirtioRngDxe/VirtioRng.h |  1 +
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/OvmfPkg/VirtioRngDxe/VirtioRng.c b/OvmfPkg/VirtioRngDxe/VirtioRng.c
index 069aed148af1..8959e51faf71 100644
--- a/OvmfPkg/VirtioRngDxe/VirtioRng.c
+++ b/OvmfPkg/VirtioRngDxe/VirtioRng.c
@@ -156,6 +156,11 @@ VirtioRngGetRNG (
   }
 
   Dev = VIRTIO_ENTROPY_SOURCE_FROM_RNG (This);
+  if (!Dev->Ready) {
+    DEBUG ((DEBUG_INFO, "%a: not ready\n", __func__));
+    return EFI_DEVICE_ERROR;
+  }
+
   //
   // Map Buffer's system physical address to device address
   //
@@ -382,6 +387,7 @@ VirtioRngInit (
   //
   Dev->Rng.GetInfo = VirtioRngGetInfo;
   Dev->Rng.GetRNG  = VirtioRngGetRNG;
+  Dev->Ready       = TRUE;
 
   return EFI_SUCCESS;
 
@@ -414,8 +420,8 @@ VirtioRngUninit (
   // VIRTIO_CFG_WRITE() returns, the host will have learned to stay away from
   // the old comms area.
   //
+  Dev->Ready = FALSE;
   Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);
-
   Dev->VirtIo->UnmapSharedBuffer (Dev->VirtIo, Dev->RingMap);
 
   VirtioRingUninit (Dev->VirtIo, &Dev->Ring);
@@ -435,7 +441,7 @@ VirtioRngExitBoot (
 {
   VIRTIO_RNG_DEV  *Dev;
 
-  DEBUG ((DEBUG_VERBOSE, "%a: Context=0x%p\n", __func__, Context));
+  DEBUG ((DEBUG_INFO, "%a: Context=0x%p\n", __func__, Context));
   //
   // Reset the device. This causes the hypervisor to forget about the virtio
   // ring.
@@ -443,7 +449,8 @@ VirtioRngExitBoot (
   // We allocated said ring in EfiBootServicesData type memory, and code
   // executing after ExitBootServices() is permitted to overwrite it.
   //
-  Dev = Context;
+  Dev        = Context;
+  Dev->Ready = FALSE;
   Dev->VirtIo->SetDeviceStatus (Dev->VirtIo, 0);
 }
 
diff --git a/OvmfPkg/VirtioRngDxe/VirtioRng.h b/OvmfPkg/VirtioRngDxe/VirtioRng.h
index 2da99540a208..3519521d6ab5 100644
--- a/OvmfPkg/VirtioRngDxe/VirtioRng.h
+++ b/OvmfPkg/VirtioRngDxe/VirtioRng.h
@@ -33,6 +33,7 @@ typedef struct {
   VRING                     Ring;           // VirtioRingInit       2
   EFI_RNG_PROTOCOL          Rng;            // VirtioRngInit        1
   VOID                      *RingMap;       // VirtioRingMap        2
+  BOOLEAN                   Ready;
 } VIRTIO_RNG_DEV;
 
 #define VIRTIO_ENTROPY_SOURCE_FROM_RNG(RngPointer) \