Messages in this thread Patch in this message | | | Date | Tue, 06 Feb 2024 12:17:52 +0000 | From | Marc Zyngier <> | Subject | Re: [Patch] memory: tegra: Skip SID override from Guest VM |
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Hi Sumit,
On Tue, 06 Feb 2024 11:48:52 +0000, Sumit Gupta <sumitg@nvidia.com> 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@nvidia.com> > --- > 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.
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