[PATCH 05/13] x86/virt/tdx: Add SEAMCALL wrappers for TDX VM/vCPU field access

Paolo Bonzini
2025-01-01T07:50:16Z

From: Rick Edgecombe <rick.p.edgecombe@intel.com>

Intel TDX protects guest VMs from malicious host and certain physical
attacks. The TDX module has TD scoped and vCPU scoped "metadata fields".
These fields are a bit like VMCS fields, and stored in data structures
maintained by the TDX module. Export 3 SEAMCALLs for use in reading and
writing these fields:

Make tdh_mng_rd() use MNG.VP.RD to read the TD scoped metadata.

Make tdh_vp_rd()/tdh_vp_wr() use TDH.VP.RD/WR to read/write the vCPU
scoped metadata.

KVM will use these by creating inline helpers that target various metadata
sizes. Export the raw SEAMCALL leaf, to avoid exporting the large number
of various sized helpers.

Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Yuan Yao <yuan.yao@intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <20241203010317.827803-6-rick.p.edgecombe@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/tdx.h | 3 +++
arch/x86/virt/vmx/tdx/tdx.c | 47 +++++++++++++++++++++++++++++++++++++
arch/x86/virt/vmx/tdx/tdx.h | 3 +++
3 files changed, 53 insertions(+)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index dbdfa7d59673..6342309fe011 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -142,9 +142,12 @@ u64 tdh_vp_addcx(struct tdx_vp *vp, struct page *tdcx_page);
u64 tdh_mng_key_config(struct tdx_td *td);
u64 tdh_mng_create(struct tdx_td *td, u64 hkid);
u64 tdh_vp_create(struct tdx_td *td, struct tdx_vp *vp);
+u64 tdh_mng_rd(struct tdx_td *td, u64 field, u64 *data);
u64 tdh_mng_key_freeid(struct tdx_td *td);
u64 tdh_mng_init(struct tdx_td *td, u64 td_params, u64 *extended_err);
u64 tdh_vp_init(struct tdx_vp *vp, u64 initial_rcx);
+u64 tdh_vp_rd(struct tdx_vp *vp, u64 field, u64 *data);
+u64 tdh_vp_wr(struct tdx_vp *vp, u64 field, u64 data, u64 mask);
u64 tdh_vp_init_apicid(struct tdx_vp *vp, u64 initial_rcx, u32 x2apicid);
u64 tdh_phymem_page_reclaim(struct page *page, u64 *tdx_pt, u64 *tdx_owner, u64 *tdx_size);
u64 tdh_phymem_cache_wb(bool resume);
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index a5036184d7d1..7cfd07772b20 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1537,6 +1537,23 @@ u64 tdh_vp_create(struct tdx_td *td, struct tdx_vp *vp)
}
EXPORT_SYMBOL_GPL(tdh_vp_create);

+u64 tdh_mng_rd(struct tdx_td *td, u64 field, u64 *data)
+{
+ struct tdx_module_args args = {
+ .rcx = tdx_tdr_pa(td),
+ .rdx = field,
+ };
+ u64 ret;
+
+ ret = seamcall_ret(TDH_MNG_RD, &args);
+
+ /* R8: Content of the field, or 0 in case of error. */
+ *data = args.r8;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tdh_mng_rd);
+
u64 tdh_mng_key_freeid(struct tdx_td *td)
{
struct tdx_module_args args = {
@@ -1574,6 +1591,36 @@ u64 tdh_vp_init(struct tdx_vp *vp, u64 initial_rcx)
}
EXPORT_SYMBOL_GPL(tdh_vp_init);

+u64 tdh_vp_rd(struct tdx_vp *vp, u64 field, u64 *data)
+{
+ struct tdx_module_args args = {
+ .rcx = tdx_tdvpr_pa(vp),
+ .rdx = field,
+ };
+ u64 ret;
+
+ ret = seamcall_ret(TDH_VP_RD, &args);
+
+ /* R8: Content of the field, or 0 in case of error. */
+ *data = args.r8;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tdh_vp_rd);
+
+u64 tdh_vp_wr(struct tdx_vp *vp, u64 field, u64 data, u64 mask)
+{
+ struct tdx_module_args args = {
+ .rcx = tdx_tdvpr_pa(vp),
+ .rdx = field,
+ .r8 = data,
+ .r9 = mask,
+ };
+
+ return seamcall(TDH_VP_WR, &args);
+}
+EXPORT_SYMBOL_GPL(tdh_vp_wr);
+
u64 tdh_vp_init_apicid(struct tdx_vp *vp, u64 initial_rcx, u32 x2apicid)
{
struct tdx_module_args args = {
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index 7a15c9afcdfa..aacd38b12989 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -19,11 +19,13 @@
#define TDH_VP_ADDCX 4
#define TDH_MNG_KEY_CONFIG 8
#define TDH_MNG_CREATE 9
+#define TDH_MNG_RD 11
#define TDH_VP_CREATE 10
#define TDH_MNG_KEY_FREEID 20
#define TDH_MNG_INIT 21
#define TDH_VP_INIT 22
#define TDH_PHYMEM_PAGE_RDMD 24
+#define TDH_VP_RD 26
#define TDH_PHYMEM_PAGE_RECLAIM 28
#define TDH_SYS_KEY_CONFIG 31
#define TDH_SYS_INIT 33
@@ -32,6 +34,7 @@
#define TDH_SYS_TDMR_INIT 36
#define TDH_PHYMEM_CACHE_WB 40
#define TDH_PHYMEM_PAGE_WBINVD 41
+#define TDH_VP_WR 43
#define TDH_SYS_CONFIG 45

/*
--
2.43.5