[kvm-unit-tests PATCH 10/33] arm: realm: Add support for changing the state of memory

Suzuki K Poulose
2024-04-12T10:36:05Z

For a Realm, the guest physical address (in reality the IPA/GPA of the VM)
has an associated state (Realm IPA State, RIPAS) which is one of :
RIPAS_RAM
RIPAS_EMPTY
RIPAS_DESTROYED

The state of the physical address decides certain behaviors. e.g., any access
to a RIPAS_EMPTY PA will generate a Synchronous External Abort back to the Realm,
from the RMM.

All "PA" that represents RAM for the Realm, must be set to RIPAS_RAM before
an access is made. When the initial image (e.g., test, DTB) of a Realm is
loaded, the hypervisor/VMM can transition the state of the loaded "area" to
RIPAS_RAM. The rest of the "RAM" must be transitioned by the test payload
before any access is made.

Similarly, a Realm could set an "IPA" to RIPAS_EMPTY, when it is about to use
the "unprotected" alias of the IPA. This is a hint for the host to reclaim the
page from the protected "IPA.

RIPAS_DESTROYED indicates that the Host has destroyed a data granule at the IPA,
without the consent from the realm and is not reachable by a Realm action.

This patchs adds supporting helpers for setting the IPA state from Realm. These
will be used later for the Realm.

Co-developed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
lib/arm/asm/rsi.h | 3 +++
lib/arm/mmu.c | 1 +
lib/arm64/asm/rsi.h | 9 +++++++
lib/arm64/rsi.c | 63 +++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 76 insertions(+)

diff --git a/lib/arm/asm/rsi.h b/lib/arm/asm/rsi.h
index 5ff8d011..98e75303 100644
--- a/lib/arm/asm/rsi.h
+++ b/lib/arm/asm/rsi.h
@@ -14,5 +14,8 @@ static inline bool is_realm(void)
}

static inline void arm_rsi_init(void) {}
+static inline void arm_set_memory_protected(unsigned long va, size_t size) {}
+static inline void arm_set_memory_protected_safe(unsigned long va, size_t size) {}
+static inline void arm_set_memory_shared(unsigned long va, size_t size) {}

#endif /* __ASMARM_RSI_H_ */
diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c
index 41a8304d..16ceffcc 100644
--- a/lib/arm/mmu.c
+++ b/lib/arm/mmu.c
@@ -13,6 +13,7 @@
#include <asm/setup.h>
#include <asm/page.h>
#include <asm/io.h>
+#include <asm/rsi.h>

#include "alloc_page.h"
#include "vmalloc.h"
diff --git a/lib/arm64/asm/rsi.h b/lib/arm64/asm/rsi.h
index 37103210..0b726684 100644
--- a/lib/arm64/asm/rsi.h
+++ b/lib/arm64/asm/rsi.h
@@ -34,4 +34,13 @@ static inline bool is_realm(void)
return rsi_present;
}

+enum ripas_t {
+ RIPAS_EMPTY,
+ RIPAS_RAM,
+};
+
+void arm_set_memory_protected(unsigned long va, size_t size);
+void arm_set_memory_protected_safe(unsigned long va, size_t size);
+void arm_set_memory_shared(unsigned long va, size_t size);
+
#endif /* __ASMARM64_RSI_H_ */
diff --git a/lib/arm64/rsi.c b/lib/arm64/rsi.c
index c4560866..e58d9660 100644
--- a/lib/arm64/rsi.c
+++ b/lib/arm64/rsi.c
@@ -71,3 +71,66 @@ void arm_rsi_init(void)
/* Set the upper bit of the IPA as the NS_SHARED pte attribute */
prot_ns_shared = (1UL << phys_mask_shift);
}
+
+static unsigned rsi_set_addr_range_state(unsigned long start, unsigned long end,
+ enum ripas_t state, unsigned int flags,
+ unsigned long *top)
+{
+ struct smccc_result res;
+
+ rsi_invoke(SMC_RSI_IPA_STATE_SET, start, end, state, flags,
+ 0, 0, 0, 0, 0, 0, 0, &res);
+ *top = res.r1;
+ return res.r0;
+}
+
+static void arm_set_memory_state(unsigned long start,
+ unsigned long size,
+ unsigned int ripas,
+ unsigned int flags)
+{
+ int ret;
+ unsigned long end, top;
+ unsigned long old_start = start;
+
+ if (!is_realm())
+ return;
+
+ start = ALIGN_DOWN(start, RSI_GRANULE_SIZE);
+ if (start != old_start)
+ size += old_start - start;
+ end = ALIGN(start + size, RSI_GRANULE_SIZE);
+ while (start != end) {
+ ret = rsi_set_addr_range_state(start, end, ripas, flags, &top);
+ assert(!ret);
+ assert(top <= end);
+ start = top;
+ }
+}
+
+/*
+ * Convert the IPA state of the given range to RIPAS_RAM, ignoring the
+ * fact that the host could have destroyed the contents and we don't
+ * rely on the previous state of the contents.
+ */
+void arm_set_memory_protected(unsigned long start, unsigned long size)
+{
+ arm_set_memory_state(start, size, RIPAS_RAM, RSI_CHANGE_DESTROYED);
+}
+
+/*
+ * Convert the IPA state of the given range to RSI_RAM, ensuring that the
+ * host has not destroyed any of the contents in the IPA range. Useful in
+ * converting a range of addresses where some of the IPA may already be in
+ * RSI_RAM state (e.g., images loaded at boot) and we want to make sure the
+ * host hasn't modified (by destroying them) the contents.
+ */
+void arm_set_memory_protected_safe(unsigned long start, unsigned long size)
+{
+ arm_set_memory_state(start, size, RIPAS_RAM, RSI_NO_CHANGE_DESTROYED);
+}
+
+void arm_set_memory_shared(unsigned long start, unsigned long size)
+{
+ arm_set_memory_state(start, size, RIPAS_EMPTY, RSI_CHANGE_DESTROYED);
+}