linux-kernel - [PATCH v3 06/14] x86/virt/tdx: Add SEAMCALL wrappers for TDX flush operations

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Message-ID: <20250115160912.617654-7-pbonzini@redhat.com>
Date: Wed, 15 Jan 2025 11:09:04 -0500
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: kai.huang@...el.com,
	rick.p.edgecombe@...el.com,
	dave.hansen@...ux.intel.com,
	yan.y.zhao@...el.com,
	Sean Christopherson <sean.j.christopherson@...el.com>,
	Isaku Yamahata <isaku.yamahata@...el.com>,
	Binbin Wu <binbin.wu@...ux.intel.com>,
	Yuan Yao <yuan.yao@...el.com>
Subject: [PATCH v3 06/14] x86/virt/tdx: Add SEAMCALL wrappers for TDX flush operations

From: Rick Edgecombe <rick.p.edgecombe@...el.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@...el.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Signed-off-by: Kai Huang <kai.huang@...el.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>
Reviewed-by: Yuan Yao <yuan.yao@...el.com>
Message-ID: <20241203010317.827803-7-rick.p.edgecombe@...el.com>
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.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 0a5ecda98713..1d84cf8e2abe 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -156,6 +156,8 @@ u64 tdh_mng_key_config(struct tdx_td *td);
 u64 tdh_mng_create(struct tdx_td *td, u16 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 387fec057bd3..83fc01bfd55d 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