Re: [PATCH 2/2] x86/virt/tdx: Use PFN directly for unmapping guest private memory

Xiaoyao Li
2026-03-19T08:56:17Z

On 3/19/2026 2:45 PM, Yan Zhao wrote:
> On Thu, Mar 19, 2026 at 11:20:48AM +0800, Xiaoyao Li wrote:
>> On 3/19/2026 8:58 AM, Yan Zhao wrote:
>>> From: Sean Christopherson <seanjc@google.com>
[...]
>>> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
>>> index a9dd75190c67..2f9d07ad1a9a 100644
>>> --- a/arch/x86/virt/vmx/tdx/tdx.c
>>> +++ b/arch/x86/virt/vmx/tdx/tdx.c
>>> @@ -730,9 +730,9 @@ static void tdx_quirk_reset_paddr(unsigned long base, unsigned long size)
>>> mb();
>>> }
>>> -void tdx_quirk_reset_page(struct page *page)
>>> +void tdx_quirk_reset_page(kvm_pfn_t pfn)
>>
>> So why keep the function tdx_quirk_reset_page() but expect passing in the
>> kvm_pfn_t? It looks werid that the name indicates to reset a page but what
>> gets passed in is a pfn.
> I thought about introducing tdx_quirk_reset_pfn(). But considering
> tdx_quirk_reset_pfn() has to be an exported API, I'm reluctant to do that.
>
> Given that even with tdx_quirk_reset_pfn(), it still expects TDX convertible
> RAM, I think having tdx_quirk_reset_page() to take pfn is still acceptable.
>
> We just don't want KVM to do pfn --> struct page --> pfn conversions.

Only tdx_sept_remove_private_spte() is doing such conversions. While
tdx_reclaim_page() and tdx_reclaim_td_control_pages() already have the
struct page natively.

So why not considering option 2?

2. keep tdx_quirk_reset_page() as-is for the cases of
tdx_reclaim_page() and tdx_reclaim_td_control_pages() that have the
struct page. But only change tdx_sept_remove_private_spte() to use
tdx_quirk_reset_paddr() directly.

It will need export tdx_quirk_reset_paddr() for KVM. I think it will be OK?