Date: Sat, 15 Nov 2025 17:42:31 GMT From: Mark Johnston <markj@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 47fdacee69ec - stable/15 - arm64/vmm: Don't set MDSCR_EL1.KDE when enabling single-stepping Message-ID: <202511151742.5AFHgVaF022439@gitrepo.freebsd.org>
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The branch stable/15 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=47fdacee69ec8ccb18df76b7584ffc5ce9862ec2 commit 47fdacee69ec8ccb18df76b7584ffc5ce9862ec2 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2025-11-05 20:54:30 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2025-11-15 17:42:08 +0000 arm64/vmm: Don't set MDSCR_EL1.KDE when enabling single-stepping When VHE mode is enabled, this results in a hang on the host. In particular, when MDSCR_EL2.KDE is set to 1 and the CPU is executing at EL_D, i.e., EL2, debug exceptions are enabled. In non-VHE mode, we call into the guest by trapping to EL2, which implicitly masks debug exceptions by setting PSTATE.D. However, in VHE mode, PSTATE.D remains clear, so when the guest's MDSCR_EL1 value is loaded, we immediately begin single-stepping. In non-VHE mode there is no need to set KDE either, so just stop setting it. Reviewed by: andrew MFC after: 3 days Sponsored by: CHERI Research Centre (EPSRC grant UKRI3001) Differential Revision: https://reviews.freebsd.org/D48965 (cherry picked from commit ac0032344ca256f758a5eeb0fd6089dd647b0496) --- sys/arm64/vmm/vmm_arm64.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/sys/arm64/vmm/vmm_arm64.c b/sys/arm64/vmm/vmm_arm64.c index e293c99a6646..5bb038dec2d3 100644 --- a/sys/arm64/vmm/vmm_arm64.c +++ b/sys/arm64/vmm/vmm_arm64.c @@ -1365,19 +1365,18 @@ vmmops_setcap(void *vcpui, int num, int val) if (val != 0) { hypctx->debug_spsr |= (hypctx->tf.tf_spsr & PSR_SS); - hypctx->debug_mdscr |= hypctx->mdscr_el1 & - (MDSCR_SS | MDSCR_KDE); + hypctx->debug_mdscr |= (hypctx->mdscr_el1 & MDSCR_SS); hypctx->tf.tf_spsr |= PSR_SS; - hypctx->mdscr_el1 |= MDSCR_SS | MDSCR_KDE; + hypctx->mdscr_el1 |= MDSCR_SS; hypctx->mdcr_el2 |= MDCR_EL2_TDE; } else { hypctx->tf.tf_spsr &= ~PSR_SS; hypctx->tf.tf_spsr |= hypctx->debug_spsr; hypctx->debug_spsr &= ~PSR_SS; - hypctx->mdscr_el1 &= ~(MDSCR_SS | MDSCR_KDE); + hypctx->mdscr_el1 &= ~MDSCR_SS; hypctx->mdscr_el1 |= hypctx->debug_mdscr; - hypctx->debug_mdscr &= ~(MDSCR_SS | MDSCR_KDE); + hypctx->debug_mdscr &= ~MDSCR_SS; hypctx->mdcr_el2 &= ~MDCR_EL2_TDE; } break;home | help
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