[dv] Document how to reproduce CI (Private) failure

related to #5786

Signed-off-by: Weicai Yang <weicai@google.com>

doc/ug/getting_started_dv.md

diff --git a/doc/ug/getting_started_dv.md b/doc/ug/getting_started_dv.md
index c3946b8..540d063 100644
--- a/doc/ug/getting_started_dv.md
+++ b/doc/ug/getting_started_dv.md
@@ -88,3 +88,27 @@
 
 The [UART DV](https://github.com/lowRISC/opentitan/tree/master/hw/ip/uart/dv) area can be used as a canonical example for making progress.
 If it is not clear on how to proceed, feel free to file an issue requesting assistance.
+
+## Reproduce a DV failure in CI
+
+Follow these steps to reproduce the failure
+
+1. Make sure the version of VCS is the same as the [one](https://github.com/lowRISC/opentitan-private-ci/blob/master/jobs.yml#L5) running in CI.
+
+2. CI runs against an auto-generated merge commit, which effectively is generated by merging the pull request (PR) into the master branch.
+This "merge" branch is updated automatically by GitHub whenever the PR branch is pushed, or when the PR is closed and re-open.
+Retrieve this exact branch by running the following (assuming "upstream" is the name of your lowrisc/opentian repository).
+```console
+$ git fetch upstream pull/<PR_number>/merge
+$ git checkout -b <temp_branch> FETCH_HEAD
+```
+
+3. This is the command that CI runs for the smoke regression.
+```console
+$ util/dvsim/dvsim.py hw/top_earlgrey/dv/top_earlgrey_sim_cfgs.hjson -i smoke --fixed-seed=1
+```
+We can only run the failed test with `--fixed-seed=1` to reproduce the failure.
+Assume there is a failure in the `uart_smoke` test. Here is the run command to reproduce it.
+```console
+$ util/dvsim/dvsim.py hw/ip/uart/dv/uart_sim_cfg.hjson -i uart_smoke --fixed-seed=1 [--waves]
+```