Reviewed-by: Caleb Schlossin <[email protected]> On 8/31/26 7:30 AM, Saif Abrar wrote: > From: Saif Abrar <[email protected]> > > SW cannot write the read-only(RO) bits of a register > and write-only(WO) bits of a register return 0 when read. > > Added ro_mask[] for each register that defines which > bits in that register are RO. > When writing to a register, the RO-bits are not updated. > > When reading a register, clear the WO bits and return the updated value. > > Tested the registers PHB_DMA_SYNC, PHB_PCIE_HOTPLUG_STATUS, PHB_PCIE_LMR, > PHB_PCIE_DLP_TRWCTL, PHB_LEM_ERROR_AND_MASK and PHB_LEM_ERROR_OR_MASK > by writing all 1's and reading back the value. > The WO bits in these registers should read back as 0. > > Add .class_size in pnv_phb4_type_info. > > Signed-off-by: Saif Abrar <[email protected]> > Reviewed-by: Cédric Le Goater <[email protected]> > Reviewed-by: "Michael S. Tsirkin" <[email protected]> > Reviewed-by: Caleb Schlossin <[email protected]> > Reviewed-by: Aditya Gupta <[email protected]> > --- > hw/pci-host/pnv_phb4.c | 79 ++++++++++++++++++++++++++--- > include/hw/pci-host/pnv_phb4.h | 13 ++++- > include/hw/pci-host/pnv_phb4_regs.h | 19 +++++-- > tests/qtest/pnv-phb-test.c | 63 ++++++++++++++++++++++- > 4 files changed, 160 insertions(+), 14 deletions(-) > > diff --git a/hw/pci-host/pnv_phb4.c b/hw/pci-host/pnv_phb4.c > index a91b8277d6..9730fd1f8a 100644 > --- a/hw/pci-host/pnv_phb4.c > +++ b/hw/pci-host/pnv_phb4.c > @@ -654,6 +654,12 @@ static void pnv_phb4_reg_write(void *opaque, hwaddr off, > uint64_t val, > return; > } > > + /* Update 'val' according to the register's RO-mask */ > + PnvPHB4Class *k = PNV_PHB4_GET_CLASS(phb); > + > + val = (phb->regs[off >> 3] & k->ro_mask[off >> 3]) | > + (val & ~(k->ro_mask[off >> 3])); > + > /* Record whether it changed */ > changed = phb->regs[off >> 3] != val; > > @@ -729,7 +735,7 @@ static void pnv_phb4_reg_write(void *opaque, hwaddr off, > uint64_t val, > case PHB_TCE_TAG_ENABLE: > case PHB_INT_NOTIFY_ADDR: > case PHB_INT_NOTIFY_INDEX: > - case PHB_DMARD_SYNC: > + case PHB_DMA_SYNC: > break; > > /* Noise on anything else */ > @@ -767,7 +773,7 @@ static uint64_t pnv_phb4_reg_read(void *opaque, hwaddr > off, unsigned size) > case PHB_VERSION: > return PNV_PHB4_PEC_GET_CLASS(phb->pec)->version; > > - /* Read-only */ > + /* Read-only */ > case PHB_PHB4_GEN_CAP: > return 0xe4b8000000000000ull; > case PHB_PHB4_TCE_CAP: > @@ -777,18 +783,49 @@ static uint64_t pnv_phb4_reg_read(void *opaque, hwaddr > off, unsigned size) > case PHB_PHB4_EEH_CAP: > return phb->big_phb ? 0x2000000000000000ull : 0x1000000000000000ull; > > + /* Write-only, read will return zeros */ > + case PHB_LEM_ERROR_AND_MASK: > + case PHB_LEM_ERROR_OR_MASK: > + return 0; > + case PHB_PCIE_DLP_TRWCTL: > + val &= ~PHB_PCIE_DLP_TRWCTL_WREN; > + return val; > /* IODA table accesses */ > case PHB_IODA_DATA0: > return pnv_phb4_ioda_read(phb); > > + /* > + * DMA sync: make it look like it's complete, > + * clear write-only read/write start sync bits. > + */ > + case PHB_DMA_SYNC: > + val = PHB_DMA_SYNC_RD_COMPLETE | > + ~(PHB_DMA_SYNC_RD_START | PHB_DMA_SYNC_WR_START); > + return val; > + > + /* > + * PCI-E Stack registers > + */ > + case PHB_PCIE_SCR: > + val |= PHB_PCIE_SCR_PLW_X16; /* RO bit */ > + break; > + > /* Link training always appears trained */ > case PHB_PCIE_DLP_TRAIN_CTL: > /* TODO: Do something sensible with speed ? */ > - return PHB_PCIE_DLP_INBAND_PRESENCE | PHB_PCIE_DLP_TL_LINKACT; > + val |= PHB_PCIE_DLP_INBAND_PRESENCE | PHB_PCIE_DLP_TL_LINKACT; > + return val; > + > + case PHB_PCIE_HOTPLUG_STATUS: > + /* Clear write-only bit */ > + val &= ~PHB_PCIE_HPSTAT_RESAMPLE; > + return val; > > - /* DMA read sync: make it look like it's complete */ > - case PHB_DMARD_SYNC: > - return PHB_DMARD_SYNC_COMPLETE; > + /* Link Management Register */ > + case PHB_PCIE_LMR: > + /* These write-only bits always read as 0 */ > + val &= ~(PHB_PCIE_LMR_CHANGELW | PHB_PCIE_LMR_RETRAINLINK); > + return val; > > /* Silent simple reads */ > case PHB_LSI_SOURCE_ID: > @@ -1633,6 +1670,30 @@ static PCIIOMMUOps pnv_phb4_iommu_ops = { > .get_address_space = pnv_phb4_dma_iommu, > }; > > +static void pnv_phb4_ro_mask_init(PnvPHB4Class *phb4c) > +{ > + /* > + * Set register specific RO-masks > + */ > + > + /* PBL - Error Injection Register (0x1910) */ > + phb4c->ro_mask[PHB_PBL_ERR_INJECT >> 3] = > + PPC_BITMASK(0, 23) | PPC_BITMASK(28, 35) | PPC_BIT(38) | PPC_BIT(46) > | > + PPC_BITMASK(49, 51) | PPC_BITMASK(55, 63); > + > + /* Reserved bits[60:63] */ > + phb4c->ro_mask[PHB_TXE_ERR_LEM_ENABLE >> 3] = > + phb4c->ro_mask[PHB_TXE_ERR_AIB_FENCE_ENABLE >> 3] = PPC_BITMASK(60, 63); > + /* Reserved bits[36:63] */ > + phb4c->ro_mask[PHB_RXE_TCE_ERR_LEM_ENABLE >> 3] = > + phb4c->ro_mask[PHB_RXE_TCE_ERR_AIB_FENCE_ENABLE >> 3] = PPC_BITMASK(36, > 63); > + /* Reserved bits[40:63] */ > + phb4c->ro_mask[PHB_ERR_LEM_ENABLE >> 3] = > + phb4c->ro_mask[PHB_ERR_AIB_FENCE_ENABLE >> 3] = PPC_BITMASK(40, 63); > + > + /* TODO: Add more RO-masks as regs are implemented in the model */ > +} > + > static void pnv_phb4_err_reg_reset(PnvPHB4 *phb) > { > STICKY_RST(PHB_ERR_STATUS, 0, PPC_BITMASK(0, 33)); > @@ -1692,6 +1753,7 @@ static void pnv_phb4_reset(Object *obj, ResetType type) > pnv_phb4_err_reg_reset(phb); > pnv_phb4_pcie_stack_reg_reset(phb); > pnv_phb4_regb_err_reg_reset(phb); > + phb->regs[PHB_PCIE_CRESET >> 3] = 0xE000000000000000; > } > > static void pnv_phb4_instance_init(Object *obj) > @@ -1866,6 +1928,7 @@ static void pnv_phb4_class_init(ObjectClass *klass, > const void *data) > DeviceClass *dc = DEVICE_CLASS(klass); > XiveNotifierClass *xfc = XIVE_NOTIFIER_CLASS(klass); > ResettableClass *rc = RESETTABLE_CLASS(klass); > + PnvPHB4Class *phb4c = PNV_PHB4_CLASS(klass); > > dc->realize = pnv_phb4_realize; > device_class_set_props(dc, pnv_phb4_properties); > @@ -1874,6 +1937,9 @@ static void pnv_phb4_class_init(ObjectClass *klass, > const void *data) > xfc->notify = pnv_phb4_xive_notify; > > rc->phases.enter = pnv_phb4_reset; > + > + /* Initialize RO-mask of registers */ > + pnv_phb4_ro_mask_init(phb4c); > } > > static const TypeInfo pnv_phb4_type_info = { > @@ -1881,6 +1947,7 @@ static const TypeInfo pnv_phb4_type_info = { > .parent = TYPE_DEVICE, > .instance_init = pnv_phb4_instance_init, > .instance_size = sizeof(PnvPHB4), > + .class_size = sizeof(PnvPHB4Class), > .class_init = pnv_phb4_class_init, > .interfaces = (const InterfaceInfo[]) { > { TYPE_XIVE_NOTIFIER }, > diff --git a/include/hw/pci-host/pnv_phb4.h b/include/hw/pci-host/pnv_phb4.h > index 95ba26db53..567a3e6e95 100644 > --- a/include/hw/pci-host/pnv_phb4.h > +++ b/include/hw/pci-host/pnv_phb4.h > @@ -19,7 +19,7 @@ > > > #define TYPE_PNV_PHB4 "pnv-phb4" > -OBJECT_DECLARE_SIMPLE_TYPE(PnvPHB4, PNV_PHB4) > +OBJECT_DECLARE_TYPE(PnvPHB4, PnvPHB4Class, PNV_PHB4) > > typedef struct PnvPhb4PecStack PnvPhb4PecStack; > > @@ -156,6 +156,17 @@ struct PnvPHB4 { > QLIST_HEAD(, PnvPhb4DMASpace) dma_spaces; > }; > > +typedef struct PnvPHB4Class { > + DeviceClass parent_class; > + > + /* > + * Read-only bitmask for registers > + * Bit value: 1 => RO bit > + * 0 => RW bit > + */ > + uint64_t ro_mask[PNV_PHB4_NUM_REGS]; > +} PnvPHB4Class; > + > void pnv_phb4_pic_print_info(PnvPHB4 *phb, GString *buf); > int pnv_phb4_pec_get_phb_id(PnvPhb4PecState *pec, int stack_index); > PnvPhb4PecState *pnv_pec_add_phb(PnvChip *chip, PnvPHB *phb, Error **errp); > diff --git a/include/hw/pci-host/pnv_phb4_regs.h > b/include/hw/pci-host/pnv_phb4_regs.h > index 59329068d3..d0962c1607 100644 > --- a/include/hw/pci-host/pnv_phb4_regs.h > +++ b/include/hw/pci-host/pnv_phb4_regs.h > @@ -180,9 +180,11 @@ > #define PHB_M64_AOMASK 0x1d0 > #define PHB_M64_UPPER_BITS 0x1f0 > #define PHB_NXLATE_PREFIX 0x1f8 > -#define PHB_DMARD_SYNC 0x200 > -#define PHB_DMARD_SYNC_START PPC_BIT(0) > -#define PHB_DMARD_SYNC_COMPLETE PPC_BIT(1) > +#define PHB_DMA_SYNC 0x200 > +#define PHB_DMA_SYNC_RD_START PPC_BIT(0) > +#define PHB_DMA_SYNC_RD_COMPLETE PPC_BIT(1) > +#define PHB_DMA_SYNC_WR_START PPC_BIT(2) > +#define PHB_DMA_SYNC_WR_COMPLETE PPC_BIT(3) > #define PHB_RTC_INVALIDATE 0x208 > #define PHB_RTC_INVALIDATE_ALL PPC_BIT(0) > #define PHB_RTC_INVALIDATE_RID PPC_BITMASK(16, 31) > @@ -387,8 +389,8 @@ > #define PHB_PCIE_SCR 0x1A00 > #define PHB_PCIE_SCR_SLOT_CAP PPC_BIT(15) > #define PHB_PCIE_SCR_MAXLINKSPEED PPC_BITMASK(32, 35) > +#define PHB_PCIE_SCR_PLW_X16 PPC_BIT(41) /* x16 */ > #define PHB_PCIE_BNR 0x1A08 > - > #define PHB_PCIE_CRESET 0x1A10 > #define PHB_PCIE_CRESET_CFG_CORE PPC_BIT(0) > #define PHB_PCIE_CRESET_TLDLP PPC_BIT(1) > @@ -397,7 +399,14 @@ > #define PHB_PCIE_CRESET_PIPE_N PPC_BIT(4) > #define PHB_PCIE_CRESET_REFCLK_N PPC_BIT(8) > #define PHB_PCIE_HOTPLUG_STATUS 0x1A20 > +#define PHB_PCIE_HPSTAT_SIMDIAG PPC_BIT(3) > +#define PHB_PCIE_HPSTAT_RESAMPLE PPC_BIT(9) > #define PHB_PCIE_HPSTAT_PRESENCE PPC_BIT(10) > +#define PHB_PCIE_HPSTAT_LINKACTIVE PPC_BIT(12) > +#define PHB_PCIE_LMR 0x1A30 > +#define PHB_PCIE_LMR_CHANGELW PPC_BIT(0) > +#define PHB_PCIE_LMR_RETRAINLINK PPC_BIT(1) > +#define PHB_PCIE_LMR_LINKACTIVE PPC_BIT(8) > > #define PHB_PCIE_DLP_TRAIN_CTL 0x1A40 > #define PHB_PCIE_DLP_LINK_WIDTH PPC_BITMASK(30, 35) > @@ -425,7 +434,7 @@ > > #define PHB_PCIE_DLP_TRWCTL 0x1A80 > #define PHB_PCIE_DLP_TRWCTL_EN PPC_BIT(0) > - > +#define PHB_PCIE_DLP_TRWCTL_WREN PPC_BIT(1) > #define PHB_PCIE_DLP_ERRLOG1 0x1AA0 > #define PHB_PCIE_DLP_ERRLOG2 0x1AA8 > #define PHB_PCIE_DLP_ERR_STATUS 0x1AB0 > diff --git a/tests/qtest/pnv-phb-test.c b/tests/qtest/pnv-phb-test.c > index 2294cf5525..23238f1582 100644 > --- a/tests/qtest/pnv-phb-test.c > +++ b/tests/qtest/pnv-phb-test.c > @@ -76,7 +76,8 @@ static void phb5_sticky_rst_test(QTestState *qts) > * Sticky reset test of PHB_PBL_ERR_STATUS. > * > * Write all 1's to reg PHB_PBL_ERR_INJECT. > - * Updated value will be copied to reg PHB_PBL_ERR_STATUS. > + * RO-only bits will not be written and > + * updated value will be copied to reg PHB_PBL_ERR_STATUS. > * > * Reset PBL core by setting PHB_PCIE_CRESET_PBL in reg PHB_PCIE_CRESET. > * Verify the sticky bits are still set. > @@ -84,7 +85,62 @@ static void phb5_sticky_rst_test(QTestState *qts) > PHB5_XSCOM_WRITE(PHB_PBL_ERR_INJECT, PPC_BITMASK(0, 63)); > PHB5_XSCOM_WRITE(PHB_PCIE_CRESET, PHB_PCIE_CRESET_PBL); /*Reset*/ > val = PHB5_XSCOM_READ(PHB_PBL_ERR_STATUS); > - g_assert_cmpuint(val, ==, (PPC_BITMASK(0, 9) | PPC_BITMASK(12, 63))); > + g_assert_cmpuint(val, ==, (PPC_BITMASK(24, 27) | PPC_BITMASK(36, 37) | > + PPC_BITMASK(39, 45) | PPC_BITMASK(47, 48) | > + PPC_BITMASK(52, 54))); > + > +} > + > +/* Check that write-only bits/regs return 0 when read */ > +static void phb4_writeonly_read_test(QTestState *qts) > +{ > + uint64_t val; > + > + /* > + * Set all bits of PHB_DMA_SYNC, > + * bits 0 and 2 are write-only and should be read as 0. > + */ > + PHB5_XSCOM_WRITE(PHB_DMA_SYNC, PPC_BITMASK(0, 63)); > + val = PHB5_XSCOM_READ(PHB_DMA_SYNC); > + g_assert_cmpuint(val & PPC_BIT(0), ==, 0x0); > + g_assert_cmpuint(val & PPC_BIT(2), ==, 0x0); > + > + /* > + * Set all bits of PHB_PCIE_HOTPLUG_STATUS, > + * bit 9 is write-only and should be read as 0. > + */ > + PHB5_XSCOM_WRITE(PHB_PCIE_HOTPLUG_STATUS, PPC_BITMASK(0, 63)); > + val = PHB5_XSCOM_READ(PHB_PCIE_HOTPLUG_STATUS); > + g_assert_cmpuint(val & PPC_BIT(9), ==, 0x0); > + > + /* > + * Set all bits of PHB_PCIE_LMR, > + * bits 0 and 1 are write-only and should be read as 0. > + */ > + PHB5_XSCOM_WRITE(PHB_PCIE_LMR, PPC_BITMASK(0, 63)); > + val = PHB5_XSCOM_READ(PHB_PCIE_LMR); > + g_assert_cmpuint(val & PPC_BIT(0), ==, 0x0); > + g_assert_cmpuint(val & PPC_BIT(1), ==, 0x0); > + > + /* > + * Set all bits of PHB_PCIE_DLP_TRWCTL, > + * write-only bit-1 should be read as 0. > + */ > + PHB5_XSCOM_WRITE(PHB_PCIE_DLP_TRWCTL, PPC_BITMASK(0, 63)); > + val = PHB5_XSCOM_READ(PHB_PCIE_DLP_TRWCTL); > + g_assert_cmpuint(val & PPC_BIT(1), ==, 0x0); > + > + /* > + * Set all bits of PHB_LEM_ERROR_AND_MASK, PHB_LEM_ERROR_OR_MASK, > + * both regs are write-only and should be read as 0. > + */ > + PHB5_XSCOM_WRITE(PHB_LEM_ERROR_AND_MASK, PPC_BITMASK(0, 63)); > + val = PHB5_XSCOM_READ(PHB_LEM_ERROR_AND_MASK); > + g_assert_cmpuint(val, ==, 0x0); > + > + PHB5_XSCOM_WRITE(PHB_LEM_ERROR_OR_MASK, PPC_BITMASK(0, 63)); > + val = PHB5_XSCOM_READ(PHB_LEM_ERROR_OR_MASK); > + g_assert_cmpuint(val, ==, 0x0); > } > > static void phb5_tests(void) > @@ -99,6 +155,9 @@ static void phb5_tests(void) > /* Check sticky reset of a register */ > phb5_sticky_rst_test(qts); > > + /* Check write-only logic */ > + phb4_writeonly_read_test(qts); > + > qtest_quit(qts); > } >
