On Wed, Aug 13, 2025, Sasha Levin wrote:
From: Sean Christopherson seanjc@google.com
[ Upstream commit 17ec2f965344ee3fd6620bef7ef68792f4ac3af0 ]
Let the guest set DEBUGCTL.RTM_DEBUG if RTM is supported according to the guest CPUID model, as debug support is supposed to be available if RTM is supported, and there are no known downsides to letting the guest debug RTM aborts.
Note, there are no known bug reports related to RTM_DEBUG, the primary motivation is to reduce the probability of breaking existing guests when a future change adds a missing consistency check on vmcs12.GUEST_DEBUGCTL (KVM currently lets L2 run with whatever hardware supports; whoops).
Note #2, KVM already emulates DR6.RTM, and doesn't restrict access to DR7.RTM.
Fixes: 83c529151ab0 ("KVM: x86: expose Intel cpu new features (HLE, RTM) to guest") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250610232010.162191-5-seanjc@google.com Signed-off-by: Sean Christopherson seanjc@google.com [ Changed guest_cpu_cap_has to guest_cpuid_has ] Signed-off-by: Sasha Levin sashal@kernel.org
Acked-by: Sean Christopherson seanjc@google.com