KVM: arm64: Flush external_mdscr_el1 to the pKVM hyp vCPU

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flush_debug_state() propagates the guest's debug_owner and the
owner-selected debug register state to the hyp vCPU, but not
external_mdscr_el1. While the host owns the debug registers, the world
switch loads MDSCR_EL1 from external_mdscr_el1 (ctxt_mdscr_el1()),
where the host's KDE/MDE/SS bits live. A non-protected guest under
KVM_GUESTDBG_USE_HW or single-step therefore runs with MDSCR_EL1.MDE/SS
clear in hardware, and its watchpoints, breakpoints and single-step
never fire.

Propagate external_mdscr_el1 to the hyp vCPU alongside the host-owned
debug state.

Fixes: 4ad3a0b87f ("KVM: arm64: Don't hijack guest context MDSCR_EL1")
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Link: https://patch.msgid.link/20260726143643.303456-2-fuad.tabba@linux.dev
Signed-off-by: Oliver Upton <oupton@kernel.org>

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Fuad Tabba 2026-07-26 15:36:42 +01:00 • committed by Oliver Upton

parent 81b2d03f8c

commit 119a9a23fb

1 changed files with 8 additions and 2 deletions

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arch/arm64/kvm/hyp/nvhe/hyp-main.c

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