Hi Sumit,
On Tue, 06 Feb 2024 11:48:52 +0000,
Sumit Gupta <sumitg@xxxxxxxxxx> wrote:
>
> MC SID register access is restricted for Guest VM.
> So, skip the SID override programming from the Guest VM.
>
> Signed-off-by: Sumit Gupta <sumitg@xxxxxxxxxx>
> ---
> drivers/memory/tegra/tegra186.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/memory/tegra/tegra186.c b/drivers/memory/tegra/tegra186.c
> index 1b3183951bfe..df441896b69d 100644
> --- a/drivers/memory/tegra/tegra186.c
> +++ b/drivers/memory/tegra/tegra186.c
> @@ -10,6 +10,7 @@
> #include <linux/of.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> +#include <asm/virt.h>
>
> #include <soc/tegra/mc.h>
>
> @@ -118,6 +119,11 @@ static int tegra186_mc_probe_device(struct tegra_mc *mc, struct device *dev)
> unsigned int i, index = 0;
> u32 sid;
>
> + if (!is_kernel_in_hyp_mode()) {
> + dev_dbg(mc->dev, "Register access not allowed\n");
> + return 0;
> + }
> +
> if (!tegra_dev_iommu_get_stream_id(dev, &sid))
> return 0;
>
> @@ -146,6 +152,11 @@ static int tegra186_mc_resume(struct tegra_mc *mc)
> #if IS_ENABLED(CONFIG_IOMMU_API)
> unsigned int i;
>
> + if (!is_kernel_in_hyp_mode()) {
> + dev_dbg(mc->dev, "Register access not allowed\n");
> + return 0;
> + }
> +
> for (i = 0; i < mc->soc->num_clients; i++) {
> const struct tegra_mc_client *client = &mc->soc->clients[i];
>
This doesn't look right. Multiple reasons:
- This helper really has nothing to do in a driver. This is
architectural stuff that is not intended for use outside of arch
core code.
- My own tegra186 HW doesn't have VHE, since it is ARMv8.0, and this
helper will always return 'false'. How could this result in
something that still works? Can I get a free CPU upgrade?
- If you assign this device to a VM and that the hypervisor doesn't
correctly virtualise it, then it is a different device and you
should simply advertise it something else. Or even better, fix your
hypervisor.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
