On Thu, Mar 09, 2023 at 05:23:19PM +0800, Zhenzhong Duan wrote:
> According to SDM 11.4.4.2 Global Status Register:
> "This field is cleared by hardware when software sets the SRTP field in the
> Global Command register. This field is set by hardware when hardware
> completes the ‘Set Root Table Pointer’ operation using the value provided
> in the Root Table Address register"
>
> Follow above spec to clear then set RTPS after finish all works, this way
> helps avoiding potential race with guest kernel. Though linux kernel is
> single threaded in writing GCMD_REG and checking GSTS_REG.
>
> Same reasion for GSTS_REG.TES
>
> Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
So I am dropping this?
> ---
> hw/i386/intel_iommu.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index faade7def8..7cba1945a3 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -2312,11 +2312,12 @@ static void vtd_handle_gcmd_qie(IntelIOMMUState *s,
> bool en)
> /* Set Root Table Pointer */
> static void vtd_handle_gcmd_srtp(IntelIOMMUState *s)
> {
> + vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_RTPS, 0);
> vtd_root_table_setup(s);
> - /* Ok - report back to driver */
> - vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_RTPS);
> vtd_reset_caches(s);
> vtd_address_space_refresh_all(s);
> + /* Ok - report back to driver */
> + vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_RTPS);
> }
>
> /* Set Interrupt Remap Table Pointer */
> @@ -2338,19 +2339,22 @@ static void vtd_handle_gcmd_te(IntelIOMMUState *s,
> bool en)
>
> if (en) {
> s->dmar_enabled = true;
> - /* Ok - report back to driver */
> - vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_TES);
> } else {
> s->dmar_enabled = false;
>
> /* Clear the index of Fault Recording Register */
> s->next_frcd_reg = 0;
> - /* Ok - report back to driver */
> - vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_TES, 0);
> }
>
> vtd_reset_caches(s);
> vtd_address_space_refresh_all(s);
> +
> + /* Ok - report back to driver */
> + if (en) {
> + vtd_set_clear_mask_long(s, DMAR_GSTS_REG, 0, VTD_GSTS_TES);
> + } else {
> + vtd_set_clear_mask_long(s, DMAR_GSTS_REG, VTD_GSTS_TES, 0);
> + }
> }
>
> /* Handle Interrupt Remap Enable/Disable */
> --
> 2.25.1
