i'm trying to install kvm with pci-passthrough, but i can't enable intel vt-d and when i execute this command
# dmesg | grep "AMD-Vi\|Intel VT-d"
nothing is displayed

Hello and welcome to LQ.

Virtual machines work best on well supported hardware. Even so there may be some bios settings that have to be enabled.

Is your hardware supported? Any bios entries for VM technology? (could be under many names)

thank you for having answered me soon enough, I am a beginner in this field.
* in fact my pc supports virtualization but I am trying to know how I know if it supports the IOMMU or not because in some document indicates that only intel VT-d supports the IOMMU and my processor supporte intel VT-x

Start here.
https://www.linux-kvm.org/page/How_t...th_VT-d_in_KVM
https://wiki.xenproject.org/wiki/VTdHowTo


https://www.linuxquestions.org/quest...ru-4175613306/

Search the web for 'Intel ark CPU NAME HERE'
Look for something like 'ark.intel.com > products >'

You must have VT-x(Virtualization) VT-d(Directed I/O)
Also a Chipset and BIOS that supports both

i.e. Search 'intel ark Xeon E5-1620v3'
Click 'ark.intel.com > products > 82763'
Look at section 'Advanced Technologies' This is what your looking for . . .
Intel® Virtualization Technology (VT-x) ‡ Yes
Intel® Virtualization Technology for Directed I/O (VT-d) ‡ Yes
Intel® VT-x with Extended Page Tables (EPT) ‡ Yes #You might need this too

After that look up your Chipset and look up or read your BIOS Manual. The option to enable it(VT-x, VT-d) shows up in the BIOS as all different names, It's not always obvious so read the manual to find out what they're calling it on that board/bios.

First things first you need to make sure the whole Hardware and BIOS stack support it then
move on to the OS/Hypervisor