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KVM: VMX: Remove explicit MMU reset in enter_rmode()

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Drop an explicit MMU reset when entering emulated real mode now that the
vCPU INIT/RESET path correctly handles conditional MMU resets, e.g. if
INIT arrives while the vCPU is in 64-bit mode.

Note, while there are multiple other direct calls to vmx_set_cr0(), i.e.
paths that change CR0 without invoking kvm_post_set_cr0(), only the INIT
emulation can reach enter_rmode().  CLTS emulation only toggles CR.TS,
VM-Exit (and late VM-Fail) emulation cannot architecturally transition to
Real Mode, and VM-Enter to Real Mode is possible if and only if
Unrestricted Guest is enabled (exposed to L1).

This effectively reverts commit 8668a3c468 ("KVM: VMX: Reset mmu
context when entering real mode")

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-8-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-07-13 09:32:45 -07:00 • committed by Paolo Bonzini
parent 665f4d9238
commit 61152cd907
1 changed files with 0 additions and 2 deletions
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2
arch/x86/kvm/vmx/vmx.c
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@ -2852,8 +2852,6 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
fix_rmode_seg(VCPU_SREG_DS, &vmx->rmode.segs[VCPU_SREG_DS]);
fix_rmode_seg(VCPU_SREG_GS, &vmx->rmode.segs[VCPU_SREG_GS]);
fix_rmode_seg(VCPU_SREG_FS, &vmx->rmode.segs[VCPU_SREG_FS]);
kvm_mmu_reset_context(vcpu);
}
int vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)