On Wed, Jun 22, 2022, Shukla, Manali wrote:
>
> On 6/16/2022 5:34 AM, Sean Christopherson wrote:
> > void __setup_mmu_range(pgd_t *cr3, phys_addr_t start, size_t len, bool nested_mmu)
> > {
> > u64 orig_opt_mask = pte_opt_mask;
> > u64 max = (u64)len + (u64)start;
> > u64 phys = start;
> >
> > /* comment goes here. */
> > pte_opt_mask |= PT_USER_MASK;
> >
> > if (use_hugepages) {
> > while (phys + LARGE_PAGE_SIZE <= max) {
> > install_large_page(cr3, phys, (void *)(ulong)phys);
> > phys += LARGE_PAGE_SIZE;
> > }
> > }
> > install_pages(cr3, phys, max - phys, (void *)(ulong)phys);
> >
> > pte_opt_mask = orig_opt_mask;
> > }
>
> Hi Sean,
>
> Thank you so much for reviewing my changes.
>
> RSVD bit test case will start failing with above implementation as we will be
> setting PT_USER_MASK bit for all host PTEs (in order to toggle CR4.SMEP)
> which will defeat one of the purpose of this patch.
/facepalm
> Right now, pte_opt_mask value which is set from setup_vm(), is overwritten in
> setup_mmu_range() for all the conditions. How about setting PT_USER_MASK
> only for nested mmu in setup_mmu_range()? It will retain the same value of
> pte_opt_mask which is set from setup_vm() in all the other cases.
Ya, that should work.
> #define IS_NESTED_MMU 1ULL
> #define USE_HUGEPAGES 2ULL
Use BIT(). And not the ULL single the param is an unsigned long, not a u64.
> void __setup_mmu_range(pgd_t *cr3, phys_addr_t start, size_t len, unsigned long mmu_flags) {
Brace goes on its own line.
> u64 orig_opt_mask = pte_opt_mask;
> u64 max = (u64)len + (u64)start;
> u64 phys = start;
>
> /* Allocate 4k pages only for nested page table, PT_USER_MASK needs to
/*
* Multi-line comments look like this.
* Line 2.
*/
> * be enabled for nested page.
> */
> if (mmu_flags & IS_NESTED_MMU)
> pte_opt_mask |= PT_USER_MASK;
>
> if (mmu_flags & USE_HUGEPAGES) {
> while (phys + LARGE_PAGE_SIZE <= max) {
> install_large_page(cr3, phys, (void *)(ulong)phys);
> phys += LARGE_PAGE_SIZE;
> }
> }
> install_pages(cr3, phys, max - phys, (void *)(ulong)phys);
>
> pte_opt_mask = orig_opt_mask;
> }
>
> static inline void setup_mmu_range(pgd_t *cr3, phys_addr_t start, size_t len) {
> __setup_mmu_range(cr3, start, len, USE_HUGEPAGES);
> }
>
> Thank you,
> Manali
