Commit 94272b08 authored by Adrian Hunter's avatar Adrian Hunter Committed by Dave Hansen
Browse files

x86/tdx: Eliminate duplicate code in tdx_clear_page() 



tdx_clear_page() and reset_tdx_pages() duplicate the TDX page clearing
logic.  Rename reset_tdx_pages() to tdx_quirk_reset_paddr() and create
tdx_quirk_reset_page() to call tdx_quirk_reset_paddr() and be used in
place of tdx_clear_page().

The new name reflects that, in fact, the clearing is necessary only for
hardware with a certain quirk.  That is dealt with in a subsequent patch
but doing the rename here avoids additional churn.

Note reset_tdx_pages() is slightly different from tdx_clear_page() because,
more appropriately, it uses mb() in place of __mb().  Except when extra
debugging is enabled (kcsan at present), mb() just calls __mb().

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarKirill A. Shutemov <kas@kernel.org>
Reviewed-by: default avatarBinbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: default avatarXiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Acked-by: default avatarKai Huang <kai.huang@intel.com>
Acked-by: default avatarSean Christopherson <seanjc@google.com>
Acked-by: default avatarVishal Annapurve <vannapurve@google.com>
Link: https://lore.kernel.org/all/20250819155811.136099-2-adrian.hunter%40intel.com
parent d8b483ba

arch/x86/include/asm/tdx.h

+2 −0
Original line number Diff line number Diff line
@@ -131,6 +131,8 @@ int tdx_guest_keyid_alloc(void); 
u32 tdx_get_nr_guest_keyids(void);

void tdx_guest_keyid_free(unsigned int keyid);



void tdx_quirk_reset_page(struct page *page);



struct tdx_td {

	/* TD root structure: */

	struct page *tdr_page;

arch/x86/kvm/vmx/tdx.c

+3 −22
Original line number Diff line number Diff line
@@ -281,25 +281,6 @@ static inline void tdx_disassociate_vp(struct kvm_vcpu *vcpu) 
	vcpu->cpu = -1;

}



static void tdx_clear_page(struct page *page)

{

	const void *zero_page = (const void *) page_to_virt(ZERO_PAGE(0));

	void *dest = page_to_virt(page);

	unsigned long i;



	/*

	 * The page could have been poisoned.  MOVDIR64B also clears

	 * the poison bit so the kernel can safely use the page again.

	 */

	for (i = 0; i < PAGE_SIZE; i += 64)

		movdir64b(dest + i, zero_page);

	/*

	 * MOVDIR64B store uses WC buffer.  Prevent following memory reads

	 * from seeing potentially poisoned cache.

	 */

	__mb();

}



static void tdx_no_vcpus_enter_start(struct kvm *kvm)

{

	struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
@@ -345,7 +326,7 @@ static int tdx_reclaim_page(struct page *page) 


	r = __tdx_reclaim_page(page);

	if (!r)

		tdx_clear_page(page);

		tdx_quirk_reset_page(page);

	return r;

}
@@ -593,7 +574,7 @@ static void tdx_reclaim_td_control_pages(struct kvm *kvm) 
		pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);

		return;

	}

	tdx_clear_page(kvm_tdx->td.tdr_page);

	tdx_quirk_reset_page(kvm_tdx->td.tdr_page);



	__free_page(kvm_tdx->td.tdr_page);

	kvm_tdx->td.tdr_page = NULL;
@@ -1714,7 +1695,7 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm, gfn_t gfn, 
		pr_tdx_error(TDH_PHYMEM_PAGE_WBINVD, err);

		return -EIO;

	}

	tdx_clear_page(page);

	tdx_quirk_reset_page(page);

	tdx_unpin(kvm, page);

	return 0;

}

arch/x86/virt/vmx/tdx/tdx.c

+8 −2
Original line number Diff line number Diff line
@@ -637,7 +637,7 @@ static int tdmrs_set_up_pamt_all(struct tdmr_info_list *tdmr_list, 
 * clear these pages.  Note this function doesn't flush cache of

 * these TDX private pages.  The caller should make sure of that.

 */

static void reset_tdx_pages(unsigned long base, unsigned long size)

static void tdx_quirk_reset_paddr(unsigned long base, unsigned long size)

{

	const void *zero_page = (const void *)page_address(ZERO_PAGE(0));

	unsigned long phys, end;
@@ -654,9 +654,15 @@ static void reset_tdx_pages(unsigned long base, unsigned long size) 
	mb();

}



void tdx_quirk_reset_page(struct page *page)

{

	tdx_quirk_reset_paddr(page_to_phys(page), PAGE_SIZE);

}

EXPORT_SYMBOL_GPL(tdx_quirk_reset_page);



static void tdmr_reset_pamt(struct tdmr_info *tdmr)

{

	tdmr_do_pamt_func(tdmr, reset_tdx_pages);

	tdmr_do_pamt_func(tdmr, tdx_quirk_reset_paddr);

}



static void tdmrs_reset_pamt_all(struct tdmr_info_list *tdmr_list)