| Message ID | 1462520796-30089-1-git-send-email-imunsie@au.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
Le 06/05/2016 09:46, Ian Munsie a écrit : > From: Ian Munsie <imunsie@au1.ibm.com> > > cxl devices typically access memory using an MMU in much the same way as > the CPU, and each context includes a state register much like the MSR in > the CPU. Like the CPU, the state register includes a bit to enable > relocation, which we currently always enable. > > In some cases, it may be desirable to allow a device to access memory > using real addresses instead of effective addresses, so this adds a new > API, cxl_set_translation_mode, that can be used to disable relocation > on a given kernel context. This can allow for the creation of a special > privileged context that the device can use if it needs relocation > disabled, and can use regular contexts at times when it needs relocation > enabled. > > This interface is only available to users of the kernel API for obvious > reasons, and will never be supported in a virtualised environment. > > This will be used by the upcoming cxl support in the mlx5 driver. > > Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Looks good to me. Reviewed-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com> Fred
On Fri, 2016-06-05 at 07:46:36 UTC, Ian Munsie wrote: > From: Ian Munsie <imunsie@au1.ibm.com> > > cxl devices typically access memory using an MMU in much the same way as > the CPU, and each context includes a state register much like the MSR in > the CPU. Like the CPU, the state register includes a bit to enable > relocation, which we currently always enable. > > In some cases, it may be desirable to allow a device to access memory > using real addresses instead of effective addresses, so this adds a new > API, cxl_set_translation_mode, that can be used to disable relocation > on a given kernel context. This can allow for the creation of a special > privileged context that the device can use if it needs relocation > disabled, and can use regular contexts at times when it needs relocation > enabled. > > This interface is only available to users of the kernel API for obvious > reasons, and will never be supported in a virtualised environment. > > This will be used by the upcoming cxl support in the mlx5 driver. > > Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/9bc8ba0e5d59a84e582004e201 cheers
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c index 8075823..6d228cc 100644 --- a/drivers/misc/cxl/api.c +++ b/drivers/misc/cxl/api.c @@ -183,6 +183,7 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed, ctx->pid = get_task_pid(task, PIDTYPE_PID); ctx->glpid = get_task_pid(task->group_leader, PIDTYPE_PID); kernel = false; + ctx->real_mode = false; } cxl_ctx_get(); @@ -219,6 +220,24 @@ void cxl_set_master(struct cxl_context *ctx) } EXPORT_SYMBOL_GPL(cxl_set_master); +int cxl_set_translation_mode(struct cxl_context *ctx, bool real_mode) +{ + if (ctx->status == STARTED) { + /* + * We could potentially update the PE and issue an update LLCMD + * to support this, but it doesn't seem to have a good use case + * since it's trivial to just create a second kernel context + * with different translation modes, so until someone convinces + * me otherwise: + */ + return -EBUSY; + } + + ctx->real_mode = real_mode; + return 0; +} +EXPORT_SYMBOL_GPL(cxl_set_translation_mode); + /* wrappers around afu_* file ops which are EXPORTED */ int cxl_fd_open(struct inode *inode, struct file *file) { diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h index dfdbfb0..6e3e485 100644 --- a/drivers/misc/cxl/cxl.h +++ b/drivers/misc/cxl/cxl.h @@ -523,6 +523,7 @@ struct cxl_context { bool pe_inserted; bool master; bool kernel; + bool real_mode; bool pending_irq; bool pending_fault; bool pending_afu_err; diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c index 769971c..c2815b9 100644 --- a/drivers/misc/cxl/guest.c +++ b/drivers/misc/cxl/guest.c @@ -617,6 +617,9 @@ static int guest_attach_process(struct cxl_context *ctx, bool kernel, u64 wed, u { pr_devel("in %s\n", __func__); + if (ctx->real_mode) + return -EPERM; + ctx->kernel = kernel; if (ctx->afu->current_mode == CXL_MODE_DIRECTED) return attach_afu_directed(ctx, wed, amr); diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c index ef494ba..ba459a9 100644 --- a/drivers/misc/cxl/native.c +++ b/drivers/misc/cxl/native.c @@ -485,8 +485,9 @@ static u64 calculate_sr(struct cxl_context *ctx) if (mfspr(SPRN_LPCR) & LPCR_TC) sr |= CXL_PSL_SR_An_TC; if (ctx->kernel) { - sr |= CXL_PSL_SR_An_R | (mfmsr() & MSR_SF); - sr |= CXL_PSL_SR_An_HV; + if (!ctx->real_mode) + sr |= CXL_PSL_SR_An_R; + sr |= (mfmsr() & MSR_SF) | CXL_PSL_SR_An_HV; } else { sr |= CXL_PSL_SR_An_PR | CXL_PSL_SR_An_R; sr &= ~(CXL_PSL_SR_An_HV); diff --git a/include/misc/cxl.h b/include/misc/cxl.h index 7d5e261..56560c5 100644 --- a/include/misc/cxl.h +++ b/include/misc/cxl.h @@ -127,6 +127,14 @@ int cxl_afu_reset(struct cxl_context *ctx); void cxl_set_master(struct cxl_context *ctx); /* + * Sets the context to use real mode memory accesses to operate with + * translation disabled. Note that this only makes sense for kernel contexts + * under bare metal, and will not work with virtualisation. May only be + * performed on stopped contexts. + */ +int cxl_set_translation_mode(struct cxl_context *ctx, bool real_mode); + +/* * Map and unmap the AFU Problem Space area. The amount and location mapped * depends on if this context is a master or slave. */