PR/59860 CVS commit: src/sys/dev/nvmm/x86

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

The following reply was made to PR port-amd64/59860; it has been noted by GNATS.

From: "Taylor R Campbell" <riastradh%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/59860 CVS commit: src/sys/dev/nvmm/x86
Date: Wed, 15 Jul 2026 01:22:21 +0000

 Module Name:	src
 Committed By:	riastradh
 Date:		Wed Jul 15 01:22:21 UTC 2026
 
 Modified Files:
 	src/sys/dev/nvmm/x86: nvmm_x86.c nvmm_x86.h nvmm_x86_svm.c
 	    nvmm_x86_vmx.c
 
 Log Message:
 nvmm: Add support for extended CPU state (XSAVE) beyond x87/SSE.
 
 New machine-dependent x86 vCPU configuration command
 NVMM_VCPU_CONF_XCR0_MASK sets the vCPU's XCR0 mask, that is, the set
 of XSAVE features that the guest sees as supported in the vCPU.  This
 command is advertised by the new machine capability
 NVMM_CAP_ARCH_VCPU_CONF_XCR0_MASK.  (Changing the XCR0 mask after the
 guest has begun execution will clear all extended CPU state for now;
 it is unlikely that hypervisor software will do this anyway.)
 
 This change doesn't expose the XSAVE area to userland in the comm
 page -- there are already machine-independent members in struct
 nvmm_comm_page at fixed offsets past the machine-dependent state so
 we can't just extend struct nvmm_vcpu_state without breaking the ABI.
 And the XSAVE area may exceed a page, but the address space for the
 virtual machine uvm object packs comm areas in consecutive pages, so
 we can't put it in the comm page at all without breaking the ABI
 another way.
 
 Instead, we can expose the XSAVE area in another location in the
 virtual machine uvm object, and create an ioctl for querying its
 object address and size so userland can mmap it.  TBD.
 
 Note: Have not tested this on CPUs with VMX/SVM but not XSAVE, or on
 CPUs with AVX-512 or AMX/ACE.  In principle the code should support
 them but we need some practice to trip over the difference between
 principle and practice.
 
 PR port-amd64/59860: nvmm: support AVX2, AVX512, &c.
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.24 -r1.25 src/sys/dev/nvmm/x86/nvmm_x86.c
 cvs rdiff -u -r1.21 -r1.22 src/sys/dev/nvmm/x86/nvmm_x86.h
 cvs rdiff -u -r1.95 -r1.96 src/sys/dev/nvmm/x86/nvmm_x86_svm.c \
     src/sys/dev/nvmm/x86/nvmm_x86_vmx.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.