x86/insn-eval: Move assign_register() out of KVM as insn_assign_reg()

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KVM's instruction emulator has a small helper, assign_register(), that
writes a value into a register following the x86 rules for writes to
general-purpose registers: an 8- or 16-bit write leaves the rest of the
register untouched, a 32-bit write zero-extends the result to 64 bits,
and a 64-bit write replaces the whole register.

The TDX guest #VE handler needs the same logic for port I/O emulation
to get 32-bit zero-extension right.  Rather than add a third copy of
the same switch, move the helper verbatim to <asm/insn-eval.h>, rename
it to insn_assign_reg(), and route KVM's callers through it.

Add <asm/insn.h> to the header's includes so it builds standalone in
callers that have not pulled it in transitively.

No functional change.

Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Cc:stable@vger.kernel.org
Link: https://patch.msgid.link/20260713133753.223947-3-kirill@shutemov.name

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Kiryl Shutsemau (Meta) 2026-07-13 14:37:52 +01:00 • committed by Dave Hansen

parent 0f63e656b1

commit 1fe104b048

2 changed files with 40 additions and 22 deletions

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36

arch/x86/include/asm/insn-eval.h

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26

arch/x86/kvm/emulate.c

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