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Commit 0cbc60d4 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: x86: Use 16-bit fields to track dirty/valid emulator GPRs



Use a u16 instead of a u32 to track the dirty/valid status of GPRs in the
emulator.  Unlike struct kvm_vcpu_arch, x86_emulate_ctxt tracks only the
"true" GPRs, i.e. doesn't include RIP in its array, and so only needs to
track 16 registers.

Note, maxing out at 16 GPRs is a fundamental property of x86-64 and will
not change barring a massive architecture update.  Legacy x86 ModRM and
SIB encodings use 3 bits for GPRs, i.e. support 8 registers.  x86-64 uses
a single bit in the REX prefix for each possible reference type to double
the number of supported GPRs to 16 registers (4 bits).

Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20220526210817.3428868-5-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent a5ba67b4
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