[PATCH 06/13] x86/virt/tdx: Add SEAMCALL wrappers for TDX flush operations

Paolo Bonzini
2025-01-01T07:50:18Z

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

Intel TDX protects guest VMs from malicious host and certain physical
attacks. The TDX module has the concept of flushing vCPUs. These flushes
include both a flush of the translation caches and also any other state
internal to the TDX module. Before freeing a KeyID, this flush operation
needs to be done. KVM will need to perform the flush on each pCPU
associated with the TD, and also perform a TD scoped operation that checks
if the flush has been done on all vCPU's associated with the TD.

Add a tdh_vp_flush() function to be used to call TDH.VP.FLUSH on each pCPU
associated with the TD during TD teardown. It will also be called when
disabling TDX and during vCPU migration between pCPUs.

Add tdh_mng_vpflushdone() to be used by KVM to call TDH.MNG.VPFLUSHDONE.
KVM will use this during TD teardown to verify that TDH.VP.FLUSH has been
called sufficiently, and advance the state machine that will allow for
reclaiming the TD's KeyID.

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>
Message-ID: <20241203010317.827803-7-rick.p.edgecombe@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/tdx.h | 2 ++
arch/x86/virt/vmx/tdx/tdx.c | 20 ++++++++++++++++++++
arch/x86/virt/vmx/tdx/tdx.h | 2 ++
3 files changed, 24 insertions(+)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 6342309fe011..8fc1836c5d09 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -143,6 +143,8 @@ 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_vp_flush(struct tdx_vp *vp);
+u64 tdh_mng_vpflushdone(struct tdx_td *td);
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);
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 7cfd07772b20..986b58b63121 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1554,6 +1554,26 @@ u64 tdh_mng_rd(struct tdx_td *td, u64 field, u64 *data)
}
EXPORT_SYMBOL_GPL(tdh_mng_rd);

+u64 tdh_vp_flush(struct tdx_vp *vp)
+{
+ struct tdx_module_args args = {
+ .rcx = tdx_tdvpr_pa(vp),
+ };
+
+ return seamcall(TDH_VP_FLUSH, &args);
+}
+EXPORT_SYMBOL_GPL(tdh_vp_flush);
+
+u64 tdh_mng_vpflushdone(struct tdx_td *td)
+{
+ struct tdx_module_args args = {
+ .rcx = tdx_tdr_pa(td),
+ };
+
+ return seamcall(TDH_MNG_VPFLUSHDONE, &args);
+}
+EXPORT_SYMBOL_GPL(tdh_mng_vpflushdone);
+
u64 tdh_mng_key_freeid(struct tdx_td *td)
{
struct tdx_module_args args = {
diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
index aacd38b12989..62cb7832c42d 100644
--- a/arch/x86/virt/vmx/tdx/tdx.h
+++ b/arch/x86/virt/vmx/tdx/tdx.h
@@ -20,6 +20,8 @@
#define TDH_MNG_KEY_CONFIG 8
#define TDH_MNG_CREATE 9
#define TDH_MNG_RD 11
+#define TDH_VP_FLUSH 18
+#define TDH_MNG_VPFLUSHDONE 19
#define TDH_VP_CREATE 10
#define TDH_MNG_KEY_FREEID 20
#define TDH_MNG_INIT 21
--
2.43.5