linux-kernel - [PATCH 1/3] KVM: SVM: Add a helper to convert a SME-aware PA back to a struct page

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Message-ID: <20240802204511.352017-2-seanjc@google.com>
Date: Fri,  2 Aug 2024 13:45:09 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] KVM: SVM: Add a helper to convert a SME-aware PA back to
 a struct page

Add __sme_pa_to_page() to pair with __sme_page_pa() and use it to replace
open coded equivalents, including for "iopm_base", which previously
avoided having to do __sme_clr() by storing the raw PA in the global
variable.

Opportunistically convert __sme_page_pa() to a helper to provide type
safety.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c |  9 ++++-----
 arch/x86/kvm/svm/svm.h | 16 +++++++++++++++-
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c115d26844f7..2c44261fda70 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1124,8 +1124,7 @@ static void svm_hardware_unsetup(void)
 	for_each_possible_cpu(cpu)
 		svm_cpu_uninit(cpu);
 
-	__free_pages(pfn_to_page(iopm_base >> PAGE_SHIFT),
-	get_order(IOPM_SIZE));
+	__free_pages(__sme_pa_to_page(iopm_base), get_order(IOPM_SIZE));
 	iopm_base = 0;
 }
 
@@ -1301,7 +1300,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu)
 	if (!kvm_hlt_in_guest(vcpu->kvm))
 		svm_set_intercept(svm, INTERCEPT_HLT);
 
-	control->iopm_base_pa = __sme_set(iopm_base);
+	control->iopm_base_pa = iopm_base;
 	control->msrpm_base_pa = __sme_set(__pa(svm->msrpm));
 	control->int_ctl = V_INTR_MASKING_MASK;
 
@@ -1503,7 +1502,7 @@ static void svm_vcpu_free(struct kvm_vcpu *vcpu)
 
 	sev_free_vcpu(vcpu);
 
-	__free_page(pfn_to_page(__sme_clr(svm->vmcb01.pa) >> PAGE_SHIFT));
+	__free_page(__sme_pa_to_page(svm->vmcb01.pa));
 	__free_pages(virt_to_page(svm->msrpm), get_order(MSRPM_SIZE));
 }
 
@@ -5250,7 +5249,7 @@ static __init int svm_hardware_setup(void)
 
 	iopm_va = page_address(iopm_pages);
 	memset(iopm_va, 0xff, PAGE_SIZE * (1 << order));
-	iopm_base = page_to_pfn(iopm_pages) << PAGE_SHIFT;
+	iopm_base = __sme_page_pa(iopm_pages);
 
 	init_msrpm_offsets();
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 76107c7d0595..2b095acdb97f 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -25,7 +25,21 @@
 #include "cpuid.h"
 #include "kvm_cache_regs.h"
 
-#define __sme_page_pa(x) __sme_set(page_to_pfn(x) << PAGE_SHIFT)
+/*
+ * Helpers to convert to/from physical addresses for pages whose address is
+ * consumed directly by hardware.  Even though it's a physical address, SVM
+ * often restricts the address to the natural width, hence 'unsigned long'
+ * instead of 'hpa_t'.
+ */
+static inline unsigned long __sme_page_pa(struct page *page)
+{
+	return __sme_set(page_to_pfn(page) << PAGE_SHIFT);
+}
+
+static inline struct page *__sme_pa_to_page(unsigned long pa)
+{
+	return pfn_to_page(__sme_clr(pa) >> PAGE_SHIFT);
+}
 
 #define	IOPM_SIZE PAGE_SIZE * 3
 #define	MSRPM_SIZE PAGE_SIZE * 2
-- 
2.46.0.rc2.264.g509ed76dc8-goog