The XIVE_ESB_SET_PQ_10 load operation is used to disable temporarily an interrupt source. If StoreEOI is active, a source could be left enabled if the load and store operations come out of order.
QEMU makes use of this offset to quiesce the sources before a migration. Enforce the load-after-store ordering always when doing so without querying the characteristics of the sources on the host. The performance penalty will be very small for QEMU. Signed-off-by: Cédric Le Goater <c...@kaod.org> --- include/hw/ppc/xive.h | 8 ++++++++ hw/intc/spapr_xive_kvm.c | 12 ++++++++++++ 2 files changed, 20 insertions(+) diff --git a/include/hw/ppc/xive.h b/include/hw/ppc/xive.h index 2c42ae92d287..c061230ea802 100644 --- a/include/hw/ppc/xive.h +++ b/include/hw/ppc/xive.h @@ -279,6 +279,14 @@ static inline hwaddr xive_source_esb_mgmt(XiveSource *xsrc, int srcno) #define XIVE_ESB_SET_PQ_10 0xe00 /* Load */ #define XIVE_ESB_SET_PQ_11 0xf00 /* Load */ +/* + * Load-after-store ordering + * + * Adding this offset to the load address will enforce + * load-after-store ordering. This is required to use with StoreEOI. + */ +#define XIVE_ESB_LD_ST_MO 0x40 /* Load-after-store ordering */ + uint8_t xive_source_esb_get(XiveSource *xsrc, uint32_t srcno); uint8_t xive_source_esb_set(XiveSource *xsrc, uint32_t srcno, uint8_t pq); diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c index 90f4509e6959..3eea4cb1c49f 100644 --- a/hw/intc/spapr_xive_kvm.c +++ b/hw/intc/spapr_xive_kvm.c @@ -317,6 +317,18 @@ static uint64_t xive_esb_rw(XiveSource *xsrc, int srcno, uint32_t offset, static uint8_t xive_esb_read(XiveSource *xsrc, int srcno, uint32_t offset) { + /* + * The XIVE_ESB_SET_PQ_10 load operation is used to disable + * temporarily an interrupt source. If StoreEOI is active, a + * source could be left enabled if the load and store operations + * come out of order. + * + * Enforce the load-after-store ordering always. + */ + if (offset == XIVE_ESB_SET_PQ_10) { + offset |= XIVE_ESB_LD_ST_MO; + } + return xive_esb_rw(xsrc, srcno, offset, 0, 0) & 0x3; } -- 2.25.4