KVM: X86: Ensure that dirty PDPTRs are loaded

KVM: X86: Ensure that dirty PDPTRs are loaded

For VMX with EPT, dirty PDPTRs need to be loaded before the next vmentry
via vmx_load_mmu_pgd()

But not all paths that call load_pdptrs() will cause vmx_load_mmu_pgd()
to be invoked.  Normally, kvm_mmu_reset_context() is used to cause
KVM_REQ_LOAD_MMU_PGD, but sometimes it is skipped:

* commit 22ab2e6b66fd("KVM: x86: do not reset mmu if CR0.CD and
CR0.NW are changed") skips kvm_mmu_reset_context() after load_pdptrs()
when changing CR0.CD and CR0.NW.

* commit 6d53f7590773("KVM: x86: Invalidate all PGDs for the current
PCID on MOV CR3 w/ flush") skips KVM_REQ_LOAD_MMU_PGD after
load_pdptrs() when rewriting the CR3 with the same value.

* commit c56815a0d51b("KVM: X86: Don't reset mmu context when
toggling X86_CR4_PGE") skips kvm_mmu_reset_context() after
load_pdptrs() when changing CR4.PGE.

Fixes: 22ab2e6b66fd ("KVM: x86: do not reset mmu if CR0.CD and CR0.NW are changed")
Fixes: 6d53f7590773 ("KVM: x86: Invalidate all PGDs for the current PCID on MOV CR3 w/ flush")
Fixes: c56815a0d51b ("KVM: X86: Don't reset mmu context when toggling X86_CR4_PGE")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211108124407.12187-2-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>