On Wed, May 25, 2022 at 10:26:04PM +0000, Sean Christopherson wrote: > 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, having 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). > > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -- Kees Cook
