On Thu, 2025-04-24 at 11:04 +0800, Yan Zhao wrote:
> Enhance the SEAMCALL wrapper tdh_mem_page_aug() to support huge pages.
>
> Verify the validity of the level and ensure that the mapping range is fully
> contained within the page folio.
>
> As a conservative solution, perform CLFLUSH on all pages to be mapped into
> the TD before invoking the SEAMCALL TDH_MEM_PAGE_AUG. This ensures that any
> dirty cache lines do not write back later and clobber TD memory.
This should have a brief background on why it doesn't use the arg - what is
deficient today. Also, an explanation of how it will be used (i.e. what types of
pages will be passed)
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
> ---
> arch/x86/virt/vmx/tdx/tdx.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index f5e2a937c1e7..a66d501b5677 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -1595,9 +1595,18 @@ u64 tdh_mem_page_aug(struct tdx_td *td, u64 gpa, int level, struct page *page, u
> .rdx = tdx_tdr_pa(td),
> .r8 = page_to_phys(page),
> };
> + unsigned long nr_pages = 1 << (level * 9);
> + struct folio *folio = page_folio(page);
> + unsigned long idx = 0;
> u64 ret;
>
> - tdx_clflush_page(page);
> + if (!(level >= TDX_PS_4K && level < TDX_PS_NR) ||
> + (folio_page_idx(folio, page) + nr_pages > folio_nr_pages(folio)))
> + return -EINVAL;
Shouldn't KVM not try to map a huge page in this situation? Doesn't seem like a
job for the SEAMCALL wrapper.
> +
> + while (nr_pages--)
> + tdx_clflush_page(nth_page(page, idx++));
clflush_cache_range() is:
static void tdx_clflush_page(struct page *page)
{
clflush_cache_range(page_to_virt(page), PAGE_SIZE);
}
So we have loops within loops... Better to add an arg to tdx_clflush_page() or
add a variant that takes one.
> +
> ret = seamcall_ret(TDH_MEM_PAGE_AUG, &args);
>
> *ext_err1 = args.rcx;
