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According to the APM Volume #2, Section 15.17, Table 15-10 (24593—Rev. 3.42—March 2024), When "GIF==0", an "Debug exception or trap, due to breakpoint register match" should be "Ignored and discarded". KVM lacks any handling of this. Even when vGIF is enabled and vGIF==0, the CPU does not ignore #DBs and relies on the VMM to do so. Handling this is possible, but the complexity is unjustified given the rarity of using HW breakpoints when GIF==0 (e.g. near VMRUN). KVM would need to intercept the #DB, temporarily disable the breakpoint, singe-step over the instruction (probably reusing NMI singe-stepping), and re-enable the breakpoint. Instead, document this as an erratum. Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Link: https://patch.msgid.link/20251030223757.2950309-1-yosry.ahmed@linux.dev Signed-off-by: Sean Christopherson <seanjc@google.com>