On Mon, Dec 08, 2025, Sasha Levin wrote:
From: Sean Christopherson seanjc@google.com
[ Upstream commit 258d985f6eb360c9c7aacd025d0dbc080a59423f ]
Use a new EMULTYPE flag, EMULTYPE_WRITE_PF_TO_SP, to track page faults on self-changing writes to shadowed page tables instead of propagating that information to the emulator via a semi-persistent vCPU flag. Using a flag in "struct kvm_vcpu_arch" is confusing, especially as implemented, as it's not at all obvious that clearing the flag only when emulation actually occurs is correct.
E.g. if KVM sets the flag and then retries the fault without ever getting to the emulator, the flag will be left set for future calls into the emulator. But because the flag is consumed if and only if both EMULTYPE_PF and EMULTYPE_ALLOW_RETRY_PF are set, and because EMULTYPE_ALLOW_RETRY_PF is deliberately not set for direct MMUs, emulated MMIO, or while L2 is active, KVM avoids false positives on a stale flag since FNAME(page_fault) is guaranteed to be run and refresh the flag before it's ultimately consumed by the tail end of reexecute_instruction().
Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20230202182817.407394-2-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Stable-dep-of: 4da3768e1820 ("KVM: SVM: Don't skip unrelated instruction if INT3/INTO is replaced") Signed-off-by: Sasha Levin sashal@kernel.org
Acked-by: Sean Christopherson seanjc@google.com