diff options
| author | Juergen Gross <jgross@suse.com> | 2026-05-08 17:39:33 +0300 |
|---|---|---|
| committer | Juergen Gross <jgross@suse.com> | 2026-05-14 19:33:05 +0300 |
| commit | 4594437880ce347ac8438758fd91543f70da1aa9 (patch) | |
| tree | 7ace2881e34f807aeacf76f91b3ca4ec215a1553 | |
| parent | 28e03f78e69cf6628b81f24777799778528a84c1 (diff) | |
| download | linux-4594437880ce347ac8438758fd91543f70da1aa9.tar.xz | |
x86/xen: Tolerate nested XEN_LAZY_MMU entering/leaving
With the support of nested lazy mmu sections it can happen that
arch_enter_lazy_mmu_mode() is being called twice without a call of
arch_leave_lazy_mmu_mode() in between, as the lazy_mmu_*() helpers
are not disabling preemption when checking for nested lazy mmu
sections.
This is a problem when running as a Xen PV guest, as
xen_enter_lazy_mmu() and xen_leave_lazy_mmu() don't tolerate this
case.
Fix that in xen_enter_lazy_mmu() and xen_leave_lazy_mmu() in order
not to hurt all other lazy mmu mode users.
Fixes: 291b3abed657 ("x86/xen: use lazy_mmu_state when context-switching")
Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <20260508143933.493013-1-jgross@suse.com>
| -rw-r--r-- | arch/x86/xen/mmu_pv.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index c80d0058efd1..3eee5f84f8a7 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -2145,7 +2145,10 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot) static void xen_enter_lazy_mmu(void) { - enter_lazy(XEN_LAZY_MMU); + preempt_disable(); + if (xen_get_lazy_mode() != XEN_LAZY_MMU) + enter_lazy(XEN_LAZY_MMU); + preempt_enable(); } static void xen_flush_lazy_mmu(void) @@ -2182,7 +2185,8 @@ static void xen_leave_lazy_mmu(void) { preempt_disable(); xen_mc_flush(); - leave_lazy(XEN_LAZY_MMU); + if (xen_get_lazy_mode() != XEN_LAZY_NONE) + leave_lazy(XEN_LAZY_MMU); preempt_enable(); } |