On Wed, 18 Oct 2023 17:31:42 +0100 Jonathan Cameron <jonathan.came...@huawei.com> wrote:
> On Wed, 18 Oct 2023 17:22:39 +0100 > Jonathan Cameron <jonathan.came...@huawei.com> wrote: > > > On Wed, 18 Oct 2023 10:40:45 -0400 > > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > > > On Thu, Oct 12, 2023 at 03:05:12PM +0100, Jonathan Cameron wrote: > > > > Establishing that only register accesses of size 4 and 8 can occur > > > > using these functions requires looking at their callers. Make it > > > > easier to see that by using switch statements. > > > > Assertions are used to enforce that the register storage is of the > > > > matching size, allowing fixed values to be used for divisors of > > > > the array indices. > > > > > > > > Suggested-by: Michael Tokarev <m...@tls.msk.ru> > > > > Signed-off-by: Jonathan Cameron <jonathan.came...@huawei.com> > > > > Reviewed-by: Fan Ni <fan...@samsung.com> > > > > > > Fails with clang: > > > > > > ../hw/cxl/cxl-component-utils.c:130:9: error: expected expression > > > QEMU_BUILD_BUG_ON(sizeof(*cregs->cache_mem_regs_write_mask) != 4); > > > ^ > > > ../include/qemu/compiler.h:76:30: note: expanded from macro > > > 'QEMU_BUILD_BUG_ON' > > > #define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x) > > > ^ > > > ../include/qemu/compiler.h:74:36: note: expanded from macro > > > 'QEMU_BUILD_BUG_MSG' > > > #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg) > > > ^ > > > 1 error generated. > > > > > > See e.g. > > > > > > https://gitlab.com/mstredhat/qemu/-/jobs/5320879531 > > > > Thanks. Will see if I can figure out what is going wrong. > > This code seems cursed. I need to figure out a way to run the CI again. > > Ran into credit problems I couldn't solve last time I tried. > > > > In meantime I can replicate this locally but not immediately obvious to me > > why it is failing. > > Any clang experts around? This seems to be fixed by reducing the scope > > case 4: > { > QEMU_BUILD_BUG_ON(); > } > I have no idea why though... > For anyone following along I asked a friendly compiler guy... https://github.com/llvm/llvm-project/issues/69572 Given that we realistically need to work around this whatever the outcome I'll add some brackets and send an update. thanks, Jonathan > > > > > Jonathan > > > > > > > > > > > > > > > --- > > > > v4: Use QEMU_BUILD_BUG_ON() instead of static_assert with missing > > > > error message. > > > > > > > > hw/cxl/cxl-component-utils.c | 65 +++++++++++++++++++++++------------- > > > > 1 file changed, 42 insertions(+), 23 deletions(-) > > > > > > > > diff --git a/hw/cxl/cxl-component-utils.c b/hw/cxl/cxl-component-utils.c > > > > index f3bbf0fd13..d1997a52e6 100644 > > > > --- a/hw/cxl/cxl-component-utils.c > > > > +++ b/hw/cxl/cxl-component-utils.c > > > > @@ -67,16 +67,24 @@ static uint64_t cxl_cache_mem_read_reg(void > > > > *opaque, hwaddr offset, > > > > CXLComponentState *cxl_cstate = opaque; > > > > ComponentRegisters *cregs = &cxl_cstate->crb; > > > > > > > > - if (size == 8) { > > > > + switch (size) { > > > > + case 4: > > > > + if (cregs->special_ops && cregs->special_ops->read) { > > > > + return cregs->special_ops->read(cxl_cstate, offset, 4); > > > > + } else { > > > > + QEMU_BUILD_BUG_ON(sizeof(*cregs->cache_mem_registers) != > > > > 4); > > > > + return cregs->cache_mem_registers[offset / 4]; > > > > + } > > > > + case 8: > > > > qemu_log_mask(LOG_UNIMP, > > > > "CXL 8 byte cache mem registers not > > > > implemented\n"); > > > > return 0; > > > > - } > > > > - > > > > - if (cregs->special_ops && cregs->special_ops->read) { > > > > - return cregs->special_ops->read(cxl_cstate, offset, size); > > > > - } else { > > > > - return cregs->cache_mem_registers[offset / > > > > sizeof(*cregs->cache_mem_registers)]; > > > > + default: > > > > + /* > > > > + * In line with specifiction limitaions on access sizes, this > > > > + * routine is not called with other sizes. > > > > + */ > > > > + g_assert_not_reached(); > > > > } > > > > } > > > > > > > > @@ -117,25 +125,36 @@ static void cxl_cache_mem_write_reg(void *opaque, > > > > hwaddr offset, uint64_t value, > > > > ComponentRegisters *cregs = &cxl_cstate->crb; > > > > uint32_t mask; > > > > > > > > - if (size == 8) { > > > > + switch (size) { > > > > + case 4: > > > > + QEMU_BUILD_BUG_ON(sizeof(*cregs->cache_mem_regs_write_mask) != > > > > 4); > > > > + QEMU_BUILD_BUG_ON(sizeof(*cregs->cache_mem_registers) != 4); > > > > + mask = cregs->cache_mem_regs_write_mask[offset / 4]; > > > > + value &= mask; > > > > + /* RO bits should remain constant. Done by reading existing > > > > value */ > > > > + value |= ~mask & cregs->cache_mem_registers[offset / 4]; > > > > + if (cregs->special_ops && cregs->special_ops->write) { > > > > + cregs->special_ops->write(cxl_cstate, offset, value, size); > > > > + return; > > > > + } > > > > + > > > > + if (offset >= A_CXL_HDM_DECODER_CAPABILITY && > > > > + offset <= A_CXL_HDM_DECODER3_TARGET_LIST_HI) { > > > > + dumb_hdm_handler(cxl_cstate, offset, value); > > > > + } else { > > > > + cregs->cache_mem_registers[offset / 4] = value; > > > > + } > > > > + return; > > > > + case 8: > > > > qemu_log_mask(LOG_UNIMP, > > > > "CXL 8 byte cache mem registers not > > > > implemented\n"); > > > > return; > > > > - } > > > > - mask = cregs->cache_mem_regs_write_mask[offset / > > > > sizeof(*cregs->cache_mem_regs_write_mask)]; > > > > - value &= mask; > > > > - /* RO bits should remain constant. Done by reading existing value > > > > */ > > > > - value |= ~mask & cregs->cache_mem_registers[offset / > > > > sizeof(*cregs->cache_mem_registers)]; > > > > - if (cregs->special_ops && cregs->special_ops->write) { > > > > - cregs->special_ops->write(cxl_cstate, offset, value, size); > > > > - return; > > > > - } > > > > - > > > > - if (offset >= A_CXL_HDM_DECODER_CAPABILITY && > > > > - offset <= A_CXL_HDM_DECODER3_TARGET_LIST_HI) { > > > > - dumb_hdm_handler(cxl_cstate, offset, value); > > > > - } else { > > > > - cregs->cache_mem_registers[offset / > > > > sizeof(*cregs->cache_mem_registers)] = value; > > > > + default: > > > > + /* > > > > + * In line with specifiction limitaions on access sizes, this > > > > + * routine is not called with other sizes. > > > > + */ > > > > + g_assert_not_reached(); > > > > } > > > > } > > > > > > > > -- > > > > 2.39.2 > > > > > > > > > > >
