I bumped into the same problem with after Windows 10 October update (1809) with my AMD Ryzen 7 2700 CPU.
There is the full solution tested on 3-Oct-2018:
Get latest Windows 10 update. (You can check your windows version by right click the left bottom corner window button, then select System) Currently, the October update (1809) won't download automatically, you have to download from here
Search "Turn windows features on or off", and check the "Windows Hypervisor Platform" (this option only appears when your Windows on version 1803 or higher)
IMPORTANT: Turn on AMD SVM! This option should be in somewhere under your BIOS menu. If your motherboard doesn't support AMD SVM, don't waste time, your computer doesn't support hardware acceleration for now.
For my Gigabyte B450 Aorus PRO Wifi with BIOS version F2, it's under:
Restart computer, click "Delete" button to open BISO menu, M.I.T. -> Advanced Frequency Settings -> Advanced CPU Core Settings -> SVM mode -> Enabled (This varied based on different motherboard manufactures)
Check your Android Studio version. The latest stable version works (3.2.1 when written)
Check your Android Emulator version. The latest stable version works (28.0.16 when written)
Now you should able to create a virtual device with a recommended system image, Oreo 27 x86 Android 8.1 (Google Play) works.
Under "Verify Configuration", you will see "Emulated Performance" -> "Graphics" is set to "Automatic" and cannot be changed, but it's OK, you emulator should still run.
If you like to use graphics hardware acceleration (Hardware - GLES 2.0), go to x86 Images, and select an ABI with x86_64 architecture.
NOTE: Do NOT install "Intel x86 Emulator Accelerator (HAXM installer)". The installation will fail, and you don't need it for AMD CPU at all!