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authorIan Munsie <imunsie@au1.ibm.com>2016-05-06 10:46:36 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2016-05-11 14:54:10 +0300
commit7a0d85d313c2066712e530e668bc02bb741a685c (patch)
treeb097194d6a8a1b8144efe32dc2222558dd64626f /drivers/misc
parent3c206fa77aaaac8cd7d4cfcd840c82495b01b288 (diff)
downloadlinux-7a0d85d313c2066712e530e668bc02bb741a685c.tar.xz
cxl: Add kernel API to allow a context to operate with relocate disabled
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> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/cxl/api.c19
-rw-r--r--drivers/misc/cxl/cxl.h1
-rw-r--r--drivers/misc/cxl/guest.c3
-rw-r--r--drivers/misc/cxl/native.c5
4 files changed, 26 insertions, 2 deletions
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index 807582335a98..6d228ccd884d 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 2823fb32fcf6..9dd3a0e7917f 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -514,6 +514,7 @@ 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 769971c065b4..c2815b97de2e 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 5d4fb9fd84bc..98f2cac45162 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -494,8 +494,9 @@ 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);