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Shutemov" Subject: [PATCH v3 14/16] KVM: TDX: Reclaim PAMT memory Date: Thu, 18 Sep 2025 16:22:22 -0700 Message-ID: <20250918232224.2202592-15-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250918232224.2202592-1-rick.p.edgecombe@intel.com> References: <20250918232224.2202592-1-rick.p.edgecombe@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Kirill A. Shutemov" Call tdx_free_page() and tdx_pamt_put() on the paths that free TDX pages. The PAMT memory holds metadata for TDX-protected memory. With Dynamic PAMT, PAMT_4K is allocated on demand. The kernel supplies the TDX module with a few pages that cover 2M of host physical memory. PAMT memory can be reclaimed when the last user is gone. It can happen in a few code paths: - On TDH.PHYMEM.PAGE.RECLAIM in tdx_reclaim_td_control_pages() and tdx_reclaim_page(). - On TDH.MEM.PAGE.REMOVE in tdx_sept_drop_private_spte(). - In tdx_sept_zap_private_spte() for pages that were in the queue to be added with TDH.MEM.PAGE.ADD, but it never happened due to an error. - In tdx_sept_free_private_spt() for SEPT pages; Add tdx_pamt_put() for memory that comes from guest_memfd and use tdx_free_page() for the rest. Signed-off-by: Kirill A. Shutemov [Minor log tweak] Signed-off-by: Rick Edgecombe --- v3: - Minor log tweak to conform kvm/x86 style. --- arch/x86/kvm/vmx/tdx.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index a55a95558557..9ee8f7f60acd 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -358,7 +358,7 @@ static void tdx_reclaim_control_page(struct page *ctrl_= page) if (tdx_reclaim_page(ctrl_page)) return; =20 - __free_page(ctrl_page); + tdx_free_page(ctrl_page); } =20 struct tdx_flush_vp_arg { @@ -589,7 +589,7 @@ static void tdx_reclaim_td_control_pages(struct kvm *kv= m) } tdx_clear_page(kvm_tdx->td.tdr_page); =20 - __free_page(kvm_tdx->td.tdr_page); + tdx_free_page(kvm_tdx->td.tdr_page); kvm_tdx->td.tdr_page =3D NULL; } =20 @@ -1759,6 +1759,7 @@ static int tdx_sept_drop_private_spte(struct kvm *kvm= , gfn_t gfn, return -EIO; } tdx_clear_page(page); + tdx_pamt_put(page); tdx_unpin(kvm, page); return 0; } @@ -1852,6 +1853,7 @@ static int tdx_sept_zap_private_spte(struct kvm *kvm,= gfn_t gfn, if (tdx_is_sept_zap_err_due_to_premap(kvm_tdx, err, entry, level) && !KVM_BUG_ON(!atomic64_read(&kvm_tdx->nr_premapped), kvm)) { atomic64_dec(&kvm_tdx->nr_premapped); + tdx_pamt_put(page); tdx_unpin(kvm, page); return 0; } @@ -1916,6 +1918,8 @@ static int tdx_sept_free_private_spt(struct kvm *kvm,= gfn_t gfn, enum pg_level level, void *private_spt) { struct kvm_tdx *kvm_tdx =3D to_kvm_tdx(kvm); + struct page *page =3D virt_to_page(private_spt); + int ret; =20 /* * free_external_spt() is only called after hkid is freed when TD is @@ -1932,7 +1936,12 @@ static int tdx_sept_free_private_spt(struct kvm *kvm= , gfn_t gfn, * The HKID assigned to this TD was already freed and cache was * already flushed. We don't have to flush again. */ - return tdx_reclaim_page(virt_to_page(private_spt)); + ret =3D tdx_reclaim_page(virt_to_page(private_spt)); + if (ret) + return ret; + + tdx_pamt_put(page); + return 0; } =20 static int tdx_sept_remove_private_spte(struct kvm *kvm, gfn_t gfn, --=20 2.51.0